ARM: dts: msm: Reduce voltage of VDD-VM to 1.35v for qca6690 in sa6155

There is no voltage drop for VDD-VM in sa6155, and 1.35v just
meets the requirement of qca6690 chip.

Change-Id: Ia39845f7fb8d30270510022b80a492e2cccfbaee
Signed-off-by: Yanfei Zhou <zyanfei@codeaurora.org>