soc: qcom: smem: Add support for suspend to disk

Add support to smem driver for suspend to disk feature.
SMEM is cleared during Hibernation and initialize SMEM
during resume from Hibernation.

Change-Id: I363eea1f959c3f2b224054884ec7569d434cb74c
Signed-off-by: Arun Prakash <app@codeaurora.org>