msm: camera: stop vfe and never restart when smmu page fault

When smmu fault happen, enforce halt and never restart.
This makes sure the HW will not be on by any chance.

Use atomic instead of spin lock to protect the race.

Change-Id: Iab3785ee7007ee6b93cc723b535f4b7bede7d852
Signed-off-by: Peter Liu <pingchie@codeaurora.org>