arm/dt: msm9625: Add RPM SMD device

Add the RPM SMD device tree node for 9625.
This will enable RPM SMD driver on 9625 which
would allow drivers to communicate with RPM.

Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>
Change-Id: I1561bfe137baaee3155d40f4559d62a786822380