msm: camera: support automode for VDD_CX

While camera preview or recording is in progress,
there are plenty of opportunities for CX to run
in auto mode. However, since these use cases
have relatively high load, running in auto mode
may have an adverse effect on stability. Therefore,
disable auto mode on MSM8974 while the camera is
in use.

Change-Id: I6cf55edfd5997d96dec5623e200174fcf3db0d54
Signed-off-by: Hody Hung <hhung@codeaurora.org>