msm-camera: isp: Handle ISPIF reset and close properly

ISPIF close and shutdown should not be executed in parallel.
Guard this situation using a mutex. Also enable AHB clock when
resetting ISPIF hardware.

Change-Id: I54eb02e2732c3a93b3f8dc8aefee2066d6d830ed
Signed-off-by: Venu Yeshala <vyeshala@codeaurora.org>
Signed-off-by: VijayaKumar T M <vtmuni@codeaurora.org>