ARM: dts: msm: Add regulator devices for SM6150

Add regulator devices for sm6150 as RPMh regulators.
This ensures that consumers are able to modify the
physical state of the PMIC regulators.

Change-Id: Ie71be199eb662e44d6b768c826d161369ad4b564
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>