drm/msm/dsi-staging: set mdp transfer time to zero for video mode panels

Mdp transfer time is needed only for command mode panels.
Add support to set mdp transfer time to zero for video
mode panels.

Change-Id: I2cccbdfc50792e0af6395c5208e580cc20336cc8
Signed-off-by: Krishna Manikandan <mkrishn@codeaurora.org>