arm/dt: msm9625: Enable ADC_TM

ADC_TM is used to enable threshold detection for VADC peripheral.
Clients can set thresholds and receive notification once the
thresholds are crossed. Clients include thermistors, battery
voltage. Add VADC channel nodes to read PA_THERM channels.

Change-Id: I5d00195adcbbd11791e4f472d259e056fc1e8cdd
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>