power: supply: Add driver for pm8916 lbc

pm8916 LBC is a Linear Battery Charger hardware block in pm8916 PMIC.

This block implements simple CC/CV charging for Li-Po batteries.
The hardware has internal state machine to switch between modes and
works mostly autonomously, only needing the limits and targets to be
set to operate.

This driver allows setting limits and enabling the LBC block, monitoring
it's state.

Signed-off-by: Nikita Travkin <nikita@trvn.ru>
Link: https://lore.kernel.org/r/20230915-pm8916-bms-lbc-v3-4-f30881e951a0@trvn.ru


Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>