dt-bindings: thermal: Add support for mmw ADC thermistors

Add new devicetree macros for the mmw ADC thermistors. The support
includes for the sensors mmw_pa1, mmw_pa2, mmw_pa3, and
sdr_mmw_therm.

Change-Id: I2e4e273bf438483f31700daf91defc6121439c52
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>