msm: mdss: do register programming only when parameters have changed

Add a check to compare whether parameters have changed from previously
set parameters and only then do reprogramming of structure. This can
save some time by not needing to reprogram the hardware and makes it
easier to debug by showing logs only when there are some changes in
parameters.

Change-Id: Ic26db2906358594fa6475010df6d6e05bc0cb4ad
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>