power: supply: max1720x: add support for reading internal and thermistor temperatures

power: supply: max1720x: add support for reading internal and thermistor temperatures

If enabled in the nPackCfg register, the Temp1, Temp2 and IntTemp registers
contain the temperature readings from the AIN1 thermistor, AIN2 thermistor
and internal die temperature respectively. Registers are shared between SBS
and normal IC functions and are always readable regardless of IC settings.

Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
Link: https://lore.kernel.org/r/20250116-max1720x-temperature-v2-1-9638969d091a@liebherr.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>