power: supply: Introduce MM8013 fuel gauge driver

power: supply: Introduce MM8013 fuel gauge driver

Add a driver for the Mitsumi MM8013 fuel gauge. The driver is a vastly
cleaned up and improved version of the one that shipped in some obscure
Lenovo downstream kernel [1], with some register definitions borrowed from
ChromeOS EC platform code [2].

[1] https://github.com/adazem009/kernel_lenovo_bengal/commit/b6b346427a871715709bd22aae449b9383f3b66b
[2] https://chromium.googlesource.com/chromiumos/platform/ec/+/master/driver/battery/mm8013.h

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20230621-topic-mm8013-v4-3-975aecd173ed@linaro.org
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>