Correct License and Copyright information on few files

gpio.h - Added missing copyright in few files.
rsa-mod-exp.h - Corrected copyright in the file.
fsl_sec.h - Added missing license in files
drivers/crypto/fsl/Makefile - Removed the incomplete GPLv2 license and replaced it with GPLv2+ license

Signed-off-by: Ruchika Gupta <ruchika.gupta@freescale.com>