msm: mdss: fix the dsi dma transaction time out on 8x10

The dsi dma data is sent during the blanking period for
the dsi video mode panel.  If the dma data are triggered
at the end of blank period, it can be in conflict with
the next video data, causing dsi controller to freeze.
This change is to trigger the dma data during the active
region, so it has enough time to be sent during the next
blank region.

Change-Id: I416bb9f82304063b802aa7f5ff09008dfdf0e6bc
Signed-off-by: Xiaoming Zhou <zhoux@codeaurora.org>