mfd: max77759: Add Maxim MAX77759 core driver

mfd: max77759: Add Maxim MAX77759 core driver

The Maxim MAX77759 is a companion PMIC for USB Type-C applications and
includes Battery Charger, Fuel Gauge, temperature sensors, USB Type-C
Port Controller (TCPC), NVMEM, and a GPIO expander.

Fuel Gauge and TCPC have separate and independent I2C addresses,
register maps, and interrupt lines and are therefore excluded from the
MFD core device driver here.

The GPIO and NVMEM interfaces are accessed via specific commands to the
built-in microprocessor. This driver implements an API that client
drivers can use for accessing those.

Signed-off-by: André Draszik <andre.draszik@linaro.org>
Acked-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://lore.kernel.org/r/20250509-max77759-mfd-v10-1-962ac15ee3ef@linaro.org
Signed-off-by: Lee Jones <lee@kernel.org>