treewide: Replace GPLv2 boilerplate/reference with SPDX - gpl-2.0_398.RULE

Based on the normalized pattern:

    this file is licensed under the terms of the gnu general public
    license version 2 this program as licensed as is without any warranty
    of any kind whether express or implied

extracted by the scancode license scanner the SPDX license identifier

    GPL-2.0-only

has been chosen to replace the boilerplate/reference.
Reviewed-by: Allison Randal <allison@lohutok.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/powerpc/kernel/kgdb.c

+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * PowerPC backend to the KGDB stub.
  *
@@ -8,10 +9,6 @@
  * PPC32 support restored by Vitaly Wool <vwool@ru.mvista.com> and
  * Sergei Shtylyov <sshtylyov@ru.mvista.com>
  * Copyright (C) 2007-2008 Wind River Systems, Inc.
- *
- * This file is licensed under the terms of the GNU General Public License
- * version 2. This program as licensed "as is" without any warranty of any
- * kind, whether express or implied.
  */
 
 #include <linux/kernel.h>