ARM: dts: msm: add proxy vote for DSI supplies for SDM845

For continuous splash screen feature the display needs to
be kept alive during the kernel boot up. Add proxy vote for
all the regulator supplies needed to keep the display alive.

Change-Id: Iec9926fb7948c774338e2d121f35e7e9455e7284
Signed-off-by: Shashank Babu Chinta Venkata <sbchin@codeaurora.org>