disp: msm: dp: Support DP display as primary

Changes to support DP display as primary. The connector should
indicate the display type as primary to the drm library.

Change-Id: Ib5f6d9d72e8c42f88d38e06ed504848b8fc52029
Signed-off-by: Xiaowen Wu <wxiaowen@codeaurora.org>
Signed-off-by: Soutrik Mukhopadhyay <quic_mukhopad@quicinc.com>
Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
Signed-off-by: Nilesh Laad <quic_nlaad@quicinc.com>