Documentation: Snapshot of msm device tree binding document

This snapshot of msm DT binding is taken as of msm-4.9 commit
<ed98af78b1815a8> ("Merge "drm/msm/dsi-staging: toggle phy
reset disable during idle pc" into msm-4.9").

Change-Id: If7e4b3ab79b7c81940996d087ae7053c4beca47d
Signed-off-by: Runmin Wang <runminw@codeaurora.org>