msm: mdss: Add support to wait for dma_done in pan display

Add support to wait for dma_done for the previous commit
before proceeding with the current commit in the pan_display
path for command mode panels.

Change-Id: Ie933ba547075c97ddb6ddbed2bc3ff08cc645010
Signed-off-by: Krishna Manikandan <mkrishn@codeaurora.org>