scsi: core: add SPDX tags to scsi midlayer files missing licensing information

Add the default kernel GPLv2 annotation to SCSI midlayer files missing any
licensing information.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/hosts.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *  hosts.c Copyright (C) 1992 Drew Eckhardt
  *          Copyright (C) 1993, 1994, 1995 Eric Youngdale

drivers/scsi/scsi.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *  scsi.c Copyright (C) 1992 Drew Eckhardt
  *         Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale

drivers/scsi/scsi_debugfs.h

+/* SPDX-License-Identifier: GPL-2.0 */
 struct request;
 struct seq_file;
 

drivers/scsi/scsi_error.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *  scsi_error.c Copyright (C) 1997 Eric Youngdale
  *

drivers/scsi/scsi_ioctl.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Changes:
  * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 08/23/2000

drivers/scsi/scsi_lib.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 1999 Eric Youngdale
  * Copyright (C) 2014 Christoph Hellwig

drivers/scsi/scsi_pm.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *	scsi_pm.c	Copyright (C) 2010 Alan Stern
  *

drivers/scsi/scsi_sysfs.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * scsi_sysfs.c
  *