power: supply: ltc2941-battery-gauge: Fix temperature units

Temperature is measured in tenths of degree Celsius.

Fixes: 085bc24d ("Add LTC2941/LTC2943 Battery Gauge Driver")
Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>