treewide: Replace GPLv2 boilerplate/reference with SPDX - gpl-2.0_320.RULE

treewide: Replace GPLv2 boilerplate/reference with SPDX - gpl-2.0_320.RULE

Based on the normalized pattern:

    this program is free software you can redistribute it and/or modify it
    under the terms of the gnu general public license version 2 as
    published by the free software foundation  this program is distributed
    as is without any warranty of any kind whether express or implied
    without even the implied warranty of merchantability or fitness for a
    particular purpose see the gnu general public license for more details

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>