drm/msm/dsi-staging: add support for secondary dsi display

Add secondary DSI panel nodes and provide corresponding power
and gpio configurations. Match secondary panel name with
command line panel name provided by boot-loader. Initialize
the secondary panel in the same way as primary panel.

CRs-Fixed: 2254681
Change-Id: I534f3b847250e080e68366765ab0e0dd177ac2ea
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>