msm: camera: isp: Self-Issue reg_update to avoid dependency

In case of last pixel stream off, camif is disabled. In this case
issue the reg update command from isp driver, instead of depending on
the userspace to avoid stream off timeout issues.

Change-Id: If6d3bc254518a065f25813191f5748b3cbc4f4d3
Signed-off-by: Harsh Shah <harshs@codeaurora.org>