msm: mdss: Allow display commit in DCM state for CMD panels

Allow display commit in DCM state for command mode panels. QDCM
tool requires explicit display kickoff during the calibration
stage in which the panel power is turned off.

Change-Id: Id6c7a0becf488ad2bfe9652b05d781384109f5c4
Signed-off-by: Zohaib Alam <zalam@codeaurora.org>
mdss: display: support dcs read with length more than 8 bytes

Add multiple reads per transaction to support dcs read with length
more than 8 bytes.

CRs-Fixed: 525839
Change-Id: I06afa826f941f88c3fe6e2f799c10d12e01708fb
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>