msm: camera:icp: Fix deadlock during ICP pagefault handling

Pagefault handling is called with mutex protection from the cam-context.
Acquiring the mutex inside the ICP driver context causes recursive locking
and deadlock.
Remove the mutex lock during pagefault handling in ICP context.

Change-Id: I21a661112e7d00f3e2e01625124bb6b73cd5d5da
Signed-off-by: Gaurav Jindal <gjindal@codeaurora.org>