soc: qcom: pasr: Add MSM PASR driver

Partial Array Self-Refresh driver is used to interface
with rpm to vote/unvote on memory self-refresh from HLOS.

Driver listens to memory hotplug notifications and decides
to vote or unvote depending on memory online and offline.
This vote is considered by RPM to avoid self-refresh on
offlined DDR segments. And hence a reduce in power consumption.

Change-Id: Ida2b36d671c6379dc3c07258a95cf15ae07a4bc0
Signed-off-by: Arun KS <arunks@codeaurora.org>