power: supply: charger-manager: Always use POWER_SUPPLY_PROP_TEMP

We were using POWER_SUPPLY_PROP_TEMP if the temperature was coming
via the fuel gauge and POWER_SUPPLY_PROP_TEMP_AMBIENT if it was
coming via the thermal framework.  Since they're mutually
exclusive in the driver and we don't know if the thermal framework
 is ambient or not, unify them both to use POWER_SUPPLY_PROP_TEMP.

Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>