msm: rmt_storage: Add support for reboot notifier

For graceful shutdown or reboot scenarios, RMT storage
sync must be completed successfuly before device shutdown.
So register with reboot notifier to initiate the RMT
storage force sync.

CRs-Fixed: 419695
CRs-Fixed: 548978
Change-Id: I6d8783d2ad2b7112fd6e84d3a9dcf033cc804a8c
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: Pratibhasagar V <pratibha@codeaurora.org>
Merge "msm: rmt_storage: Add support for reboot notifier"