ARM: dts: msm: Add VADC and ADC_TM channels

Add PMA8084 VADC channels to read system thermistors and
voltage channels. Thermistors are read through the AMUX
channels and vbatt is read through MPP4. MPP4 here is configured
as an analog input to AMUX8 to support reading vbatt channel.
Add the system thermistor and vbatt channels under ADC_TM
to support recurring measurements.

Change-Id: I6b7969284ce8f2b97f3a8fd63b1a2b2866130e56
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>