Change license to GPLv2

Change-Id: Id5969d2721feb8d1552e310d7117c239452eea01
Signed-off-by: Sylvain Trosset <trosset.sylvain@gmail.com>
Git-commit: 17af251b665f5ab66b03ef851027684b2848caf7
Git-repo: https://code.google.com/p/tee-mobicore-driver.kernel/


Signed-off-by: Keith Fallows <keithf@codeaurora.org>
Acked-by: Tony Hamilton <tonyh@qti.qualcomm.com>