msm: subsystem_restart: Mark watchdog IRQ as a wakeup IRQ

Add power management wakeup support to the watchdog IRQ.
Enable the wakeup mode when the subsystem is powered
on and disable on subsystem shutdown.

Change-Id: Id11722fe9c7329147430d8e3450e8747da8fb4ea
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>