msm: mdss: update panel PHY timings during resolution switch

During dynamic resolution switch update the DSI PHY timings
for panel based on the new porch values. Also calculate the
new frame rate as per new porch values.

Change-Id: I683bf1255c77a2575567847cef5edcfb5529b69d
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>