fix the following 'make includecheck' warning:

  arch/arm/plat-s3c64xx/pm.c: plat/regs-gpio.h is included more than once.
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Acked-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>