ARM: dts: msm: add pm8937 regulator devices for msm8937

Add new files pm8937-rpm-regulator.dtsi and msm8937-regulator.dtsi
which contain regulator devices found in PM8937 chips.

These files are based upon msm-pm8937-rpm-regulator.dtsi and
msm8937-regulator.dtsi files found in the msm-3.18 branch as of:

'commit c0b3f609196f ("ARM: dts: msm: Remove GPU mempool for msm8909")'

CRs-Fixed: 2160311
Change-Id: I4a43ff7b002e878cb13ab0a215a127bec6fca639
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>