ARM: dts: msm: specify SBUx and VPH_PWR channel on MTP and QRD

In SM8150 platforms, channel ADC_SBUx is used for SBU1/2 resistance
measurement by VADC, and channel VPH_PWR for system power input/output
voltage measurement.

Change-Id: I4083b6e082b8186444f6e7c63f93cadcb1848aab
Signed-off-by: Harry Yang <harryy@codeaurora.org>