msm: clock-8610: add mdp pixel clock and dsi clock

MDP pixel clock is the core clock for the MDP3 core, and DSI clock is
the core clock for the DSI controller.

Change-Id: I6276a0ae8632699f177ef31bb5b9518547265fd8
Signed-off-by: Xiaoming Zhou <zhoux@codeaurora.org>