power: supply: axp20x_battery: Make iio and battery config per device

Move the configuration of battery specific information and available
iio channels from the probe function to a device specific routine,
allowing us to use this driver for devices with slightly different
configurations (such as the AXP717).

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240821215456.962564-4-macroalpha82@gmail.com


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