treewide: Replace GPLv2 boilerplate/reference with SPDX - gpl-2.0_152.RULE

Based on the normalized pattern:

    this software is distributed under the terms of the gnu general public
    license ( gpl ) version 2 as published by the free software foundation
    this software is provided by the copyright holders and contributors as
    is and any express or implied warranties including but not limited to
    the implied warranties of merchantability and fitness for a particular
    purpose are disclaimed in no event shall the copyright owner or
    contributors be liable for any direct indirect incidental special
    exemplary or consequential damages (including but not limited to
    procurement of substitute goods or services loss of use data or
    profits or business interruption) however caused and on any theory of
    liability whether in contract strict liability or tort (including
    negligence or otherwise) arising in any way out of the use of this
    software even if advised of the possibility of such damage

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>