treewide: Replace GPLv2 boilerplate/reference with SPDX - gpl-2.0_160.RULE

treewide: Replace GPLv2 boilerplate/reference with SPDX - gpl-2.0_160.RULE

Based on the normalized pattern:

    the code contained herein is licensed under the gnu general public
    license you may obtain a copy of the gnu general public license
    version 2 at the following locations:  http://www opensource
    org/licenses/gpl-license html http://www gnu org/copyleft/gpl html

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>