ARM: dts: msm: Add UFS's Vcc voltage level entry for SDM845 QVR platform

Allows selecting the UFS's Vcc voltage level via the device tree setting.
If the device tree does not specify the UFS's vcc-voltage-level, the
default values specified in the code will be used.

Change-Id: I405e4a041840ead114067c550a69f726deb86422
Signed-off-by: Can Guo <cang@codeaurora.org>