dt-bindings: power: supply: axp20x: add AXP813 AC power DT binding

The AXP803/AXP813 AC power supply can limit input current and voltage.

Signed-off-by: Oskari Lemmela <oskari@lemmela.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Quentin Schulz <quentin.schulz@bootlin.com>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Tested-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>