hwmon: pm8xxx-adc: Add BATT_ID_THERM configuration

PM8018 ADC arbiter uses a single AMUX8 channel to
read either battery id or battery tempertaure. On
existing platforms these pins are grounded.

Add default configuration to read battery ID. If clients
need to read the battery temperature instead, follow the
instructions in the comments for the ADC channel listing.
Clients would need to update the scaling function in the
channel configuration to use the appropriate battery
thermistor scaling function.

CRs-Fixed: 350907
Change-Id: Ia3a8054c9be1e90d2076fd583ef8480353b78c6d
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
2 files changed