treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 492

Based on 1 normalized pattern(s):

  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 of the license this program
  is distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose good title or non infringement 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 in 3 file(s).

Bucket: GOODTITLE

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>