ARM: EXYNOS4: Fix compilation break

The patch "ARM: SAMSUNG: Add support for pre-sleep/post-restore gpio
control" broke compilation on Exynos4 platform with power management
enabled. This patch adds missing stubs that fixes this issue.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>