msm: mdss: increase mdp core clock to match panel pixel clock

In case of command mode panel, the pixel clock can be increased in order
to finish transfer faster. In such cases we can increase the core clock
in order to match the pixel clock and finish the transfer faster.

Change-Id: I44a01e42c687ce20d4dbfa068478ad438433a581
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>