drm/msm/sde: synchronize mdp clk with frame update

There is a race condition between the commit and
the validate, where the mdp clock or the bandwidth
can be updated for voting before the actual configuration
is taking place.

Fix this issue by caching the performance values in the crtc
till the current hw configuration is on-going.

Change-Id: Icc71c4f58cbc305529d308335f44b8c05702ebee
Signed-off-by: Abhinav Kumar <abhinavk@codeaurora.org>