msm: msm_dsps: Disable the DSPS watchdog before shutdown

The DSPS watchdog timer continues counting even after
the DSPS is shutdown. This may cause a spurious watchdog
interrupt after the DSPS is powered up, before the software
running on the processor can re-init the watchdog. Disable
the watchdog before shutting down the watchdog.

Change-Id: I169e690b82ae05617e096ac832d757a110f673a4
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
(cherry picked from commit c84f66e2f518dcb9f0931a5a1b65bc770ee23d13)

Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
(cherry picked from commit c9b48441a43985671779dc247356cb1313573722)