msm: mdss: Add mdp clock optimization for mdp3 targets

For the panels of resolution less than qHD, ppp can work
in SVS when there is no scaling involved. Optimize the
clock rates based on this for 8909 target.

Change-Id: I0357edcb3f1bc9e4f821a897b6740ac60b4fd44a
Signed-off-by: Shivaraj Shetty <shivaraj@codeaurora.org>