msm: ssr: Add notification to indicate a device restart

Send a 'soc_reset' notification to the drivers that have
registered for notifications about the subsystem when subsystem
restart has been called with the restart level set to SOC.
The drivers can then do the necessary cleanup/logging before a
kernel panic is trigerred.

Change-Id: Ie6dd131534f7380065c95795a62072dc712715d6
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>