ARM: dts: msm: add regulator devices for sdmmagpie

Add RPMH/Stub based regulator device nodes for
sdmmagpie which are used by clients to vote on their
supply regulators. Stub regulators are can be used
on platforms where PMIC or RPMH support is not present.

Change-Id: Iea8e640430bf27ca7756e062f3c958e691db5e58
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>