msm: camera: reqmgr: Add support to modify timer for long exposure

In case of long exposure shots, watchdog timer needs to be modified
according to the requested value to avoid trigger. Add support for
modifying timer value and changing it back to normal.

CRs-Fixed: 2530691
Change-Id: I97bdd92d2ed461066bbf746bc6293094a444f8a5
Signed-off-by: Mukund Madhusudan Atre <matre@codeaurora.org>
Signed-off-by: Karthik Anantha Ram <kartanan@codeaurora.org>