msm: smd: notify RPM processor of SMD SSR events

When SSR occurs, SMD may update channels interacting with the RPM
processor, which requires Apps to send interrupt notifications to RPM
in order for RPM to process any such updates.

Change-Id: Iaaa3411553c38c14414684c563532ea14329aa2b
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>