video: msm: Increase MDP clock multiplier

* The porch values used on Samsung's panel drivers are very tight, and	9
   cause the MDP clock rate calculation to be right on the edge of	10
   stability. Underrun was occurring when FLIP_LR was set on any pipe,	11
   which is the case for 180 rotation (FLIP_LR|FLIP_UD).	12
 * Raise the multiplier from 1.15 to 2 to fix the underrun.