drm/msm/dsi-staging: add support to batch commands and kickoff

Add support to group commands until last_command
bit is set in the dtsi commands packing array
and transfer the batch of commands in one dma kickoff.

Change-Id: I0b6d91f2e26553c37f1e6adfc44542312c18340f
Signed-off-by: Vara Reddy <varar@codeaurora.org>