treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 450

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 version 2 as
  published bythe free software foundation

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 5 file(s).

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