video: msm: Enable mdp clock for histogram and histLUT

Enable the mdp clock for histogram and histogram LUT to ensure that the
clock remains enabled when they are being accessed.

Change-Id: Ic744f2ee96b64442f23ba19aa1c38552c0dad83a
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>
(cherry picked from commit e782ceab26e38590cd49a9bb273da1dbf1984ccd)