msm: mdss: Multiple panel support

MDSS DSI and clock configuration depend on the panel. Add mdss-panel-id
to read the panel id from device tree. And then driver is able to use it
to set the panel specific configs

Change-Id: Icaf07a2aa0d5b792a86223971feed5c956ab1e1c
Signed-off-by: Sungmin Kwon <sungmin.kwon@lge.com>
Signed-off-by: Sooduek Kim <sooduek.kim@lge.com>
Signed-off-by: Han Jun-Yeong <junyeong.han@lge.com>
Signed-off-by: Devin Kim <dojip.kim@lge.com>

Conflicts:
	drivers/video/msm/mdss/mdss_dsi_panel.c