This patch adds Exynos SROM controller driver which will handle
save restore of SROM registers during S2R.

Signed-off-by: Pankaj Dubey
Reviewed-by: Krzysztof Kozlowski
[p.fedin@samsung.com: tested on SMDK5410]
Tested-by: Pavel Fedin
Signed-off-by: Kukjin Kim
[k.kozlowski: Minor COMPILE_TEST adjustments in Kconfig entries]
Signed-off-by: Krzysztof Kozlowski