msm: mdss: MDP clock optimization for single layer video playback

MDP core clock bumping is not required for single layer video
playback in 8x26 targets. Hence add revision check to avoid fudge
factor.

Change-Id: I1b0ccb4ef50514f705845b0218fa6ca0d28c1779
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>