soc: qcom: add RPM SMD driver

This is a snapshot of the RPM-SMD driver as of msm-3.10 commit

acdce027751d5a7488b283f0ce3111f873a5816d (Merge "defconfig: arm64: Enable
ONESHOT_SYNC for msm8994")

Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
[abhimany: resolve trivial merge conflicts]
Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>