treewide: Replace GPLv2 boilerplate/reference with SPDX - gpl-2.0_318.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 as published by the
    free software foundation version 2  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
    you should have received a copy of the gnu general public license
    along with this program if not write to the free software foundation
    inc 59 temple place suite 330 boston ma 02111-1307 usa

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>