msm: mdss: added support to change panel resolution dynamically

Helpful in changing the panel resoultion on the fly with the help of
debugfs nodes and when used along with simulated panels, it allows to
test different panel configurations dynamically.

Change-Id: I9cdf82e4fffd3dd618ee97601f169d72ab76a473
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>