ARM: EXYNOS: Support suspend and resume for EXYNOS5250

This patch adds function for suspend and resume of Exynos5250.

Signed-off-by: Jongpill Lee <boyko.lee@samsung.com>
[kgene.kim@samsung.com: re-worked on top of v3.4-rc7]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>