ARM: SAMSUNG: Add support for pre-sleep/post-restore gpio control

Add a callback so that per-arch can do pre-sleep and post-resume
gpio configuration so that for the S3C64XX, the GPIO configuration
is restored before the sleep mode is cleared.

For the S3C64XX case, it means that the GPIOs get set back to normal
operation after the restore code puts the original configurations
back in after the

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>