video: msm: Clear and disable histogram interrupt

When the histogram is disabled, its interrupt should also be disabled and
cleared.

Note: only applicable to MDP4.0 onwards as earlier versions of the MDP
expect the histogram interrupt to be left enabled after running
mdp_histogram_ctrl.

CRs-Fixed: 310429
Change-Id: I5a8df4fdcc41520e1ed0af970a8628479a4645a6
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>