staging: erofs: update source file headers

- Use the correct style for all SPDX License Identifiers;
- Get rid of the unnecessary license boilerplate;
- Use "GPL-2.0-only" instead of "GPL-2.0" suggested-by Stephen.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190731155752.210602-2-gaoxiang25@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/erofs/Kconfig

-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: GPL-2.0-only
 
 config EROFS_FS
 	tristate "EROFS filesystem support"

drivers/staging/erofs/Makefile

-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: GPL-2.0-only
 
 EROFS_VERSION = "1.0pre1"
 

drivers/staging/erofs/compress.h

-/* SPDX-License-Identifier: GPL-2.0 */
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * linux/drivers/staging/erofs/compress.h
  *

drivers/staging/erofs/data.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/data.c
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #include "internal.h"
 #include <linux/prefetch.h>

drivers/staging/erofs/decompressor.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/decompressor.c
  *

drivers/staging/erofs/dir.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/dir.c
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #include "internal.h"
 

drivers/staging/erofs/erofs_fs.h

-/* SPDX-License-Identifier: GPL-2.0 OR Apache-2.0
- *
+/* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
+/*
  * linux/drivers/staging/erofs/erofs_fs.h
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is dual-licensed; you may select either the GNU General Public
- * License version 2 or Apache License, Version 2.0. See the file COPYING
- * in the main directory of the Linux distribution for more details.
  */
 #ifndef __EROFS_FS_H
 #define __EROFS_FS_H

drivers/staging/erofs/include/linux/tagptr.h

-/* SPDX-License-Identifier: GPL-2.0
- *
- * Tagged pointer implementation
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * A tagged pointer implementation
  *
  * Copyright (C) 2018 Gao Xiang <gaoxiang25@huawei.com>
  */

drivers/staging/erofs/include/trace/events/erofs.h

-/* SPDX-License-Identifier: GPL-2.0 */
+/* SPDX-License-Identifier: GPL-2.0-only */
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM erofs
 

drivers/staging/erofs/inode.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/inode.c
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #include "xattr.h"
 

drivers/staging/erofs/internal.h

-/* SPDX-License-Identifier: GPL-2.0
- *
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
  * linux/drivers/staging/erofs/internal.h
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #ifndef __INTERNAL_H
 #define __INTERNAL_H

drivers/staging/erofs/namei.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/namei.c
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #include "internal.h"
 #include "xattr.h"

drivers/staging/erofs/super.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/super.c
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #include <linux/module.h>
 #include <linux/buffer_head.h>

drivers/staging/erofs/unzip_pagevec.h

-/* SPDX-License-Identifier: GPL-2.0
- *
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
  * linux/drivers/staging/erofs/unzip_pagevec.h
  *
  * Copyright (C) 2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #ifndef __EROFS_UNZIP_PAGEVEC_H
 #define __EROFS_UNZIP_PAGEVEC_H

drivers/staging/erofs/unzip_vle.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/unzip_vle.c
  *
  * Copyright (C) 2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #include "unzip_vle.h"
 #include "compress.h"

drivers/staging/erofs/unzip_vle.h

-/* SPDX-License-Identifier: GPL-2.0
- *
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
  * linux/drivers/staging/erofs/unzip_vle.h
  *
  * Copyright (C) 2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #ifndef __EROFS_FS_UNZIP_VLE_H
 #define __EROFS_FS_UNZIP_VLE_H

drivers/staging/erofs/utils.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/utils.c
  *
  * Copyright (C) 2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
-
 #include "internal.h"
 #include <linux/pagevec.h>
 

drivers/staging/erofs/xattr.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/xattr.c
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #include <linux/security.h>
 #include "xattr.h"

drivers/staging/erofs/xattr.h

-/* SPDX-License-Identifier: GPL-2.0
- *
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
  * linux/drivers/staging/erofs/xattr.h
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             http://www.huawei.com/
  * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
  */
 #ifndef __EROFS_XATTR_H
 #define __EROFS_XATTR_H

drivers/staging/erofs/zmap.c

-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/drivers/staging/erofs/zmap.c
  *