ARM: dts: msm: add DSI PHY regulators to MDSS DSI node

Currently, we turn off the DSI ctrl/PHY regulators during suspend as
part of panel power control API which might cause the regulators to be
turned off before the DSI controller and PHY is disabled. Hence, add the
DSI PHY regulators to the MDSS DSI node for multiple chipsets and control
these regulators as part of DSI clock control API.

Change-Id: I134ad45155605db049088efb5d819e142bafdc12
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>