platform: msm8952: add support for display clocks for 8956

msm8956 has a different clock plan for MDP clock when compared
to msm8952 and this includes GPLL6. msm8956 supports two DSI
devices. Add support for MDP clock, escape clock for DSI1
controller and update the 8952 clock header with the register
offsets for DSI1 clocks.

Change-Id: I9dd7f59f908f98f7dbf99ff277015f3ec4c4f172
3 files changed