disp: msm: read mdp intf line count and trigger dma accordingly

This change reads the video line count from
MDP_INTF_LINE_COUNT register and checks whether
DMA trigger happens close to the schedule line.
If it is not close to the schedule line, then DMA
command transfer is triggered. Without this change
there is a chance that when 2 DSI's with broadcast,
schedule enabled, the DMA command gets triggered close
to the schedule line which could cause DMA timeout.

Change-Id: Ida92e63e46b4cc703d57ce24097834f810776aa8
Signed-off-by: Harigovindan P <harigovi@codeaurora.org>