drm/msm/dsi-staging: add support for 2 DSI active displays

This change adds support for 2 DSI active displays by creating 2
separate primary and secondary nodes. It has support for handling
incorrect panel input from UEFI commandline.

Change-Id: I24c69aee064b60b3650fef63299e1c4437808836
Signed-off-by: Tharun Raj Soma <tsoma@codeaurora.org>