msm: subsystem_restart: Add workqueue for device restart

Add a workqueue for notifying the subsystems regarding a device
restart and triggering a kernel panic. This prevents preemtible
code from executing in atomic execution paths.

Change-Id: Id68dd4d10514a3f59180b6cf837de2e6685c2cd6
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>