msm: cpp: Synchronize user thread and firmware timeout sequence

If sub device node shutdown is triggered due to daemon crash while
firmware has timed out and reload is in progress a device crash
is observed. The shutdown sequence cleans up the cpp node and
causes an invalid access in timeout function causing device crash.
Synchronize user thread and firmware timeout sequence.

Change-Id: Ie0c68fe768035296350387df1ab88de90b74a688
Signed-off-by: Krishnankutty Kolathappilly <kkolatha@codeaurora.org>