dt-bindings: platform: msm: Add DT bindings for qpnp-revid driver

Add DT bindings for QPNP REVID driver that provides the QTI PMIC
revision information for other peripheral drivers upon request.

This is taken as a snapshot from msm-4.14 kernel
'commit 9bb584ae3a9d ("msm/sde/rotator: Add rev checks for sdmmagpie")'

Change-Id: I966a03d2594c3985083d4083cb7301fe48a93f0f
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>