msm: mdss: provide interface to pass BLIT fps for mdp3

On 8909 for PPP bandwidth voting driver will either vote
for 60fps or will reduce it based on some assumptions.
Add interface to send the fps information from userspace
and use the same for bandwidth requirement calculations.

Change-Id: Ic42a512950691c38c48aad12f4f16e623f2f9af1
Signed-off-by: Shivaraj Shetty <shivaraj@codeaurora.org>