ARM: dts: msm: Add rpm-regulator node to notify APC corner on 8952

Add a regulator interface to notify the APC operating corner to RPM.
This can be used to apply logic requiring the current APC corner
details.

Also, add the cpr-regulator as a consumer for this regulator.

CRs-Fixed: 818873
Change-Id: I555b57d127b713bfcb35f8bda6f0b432a77f5931
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>