dt-bindings: Add devicetree bindings to devicetree project

Add devicetree bindings snapshot to the devicetree project.
This snapshot is taken as of
'commit f3dd4aae (Merge
"platform: qpnp-revid: Add REVID support for PM7250B")' of
the kernel project.

Change-Id: I5e0ec0eae63ff9c071b2924bd84c5b20d3f6554d