power: supply: sc27xx: Add fuel gauge calibration

This patch adds support to read calibration values from the eFuse controller
to calibrate the ADC values corresponding to current and voltage, which can
make the current and voltage data more accurate.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>