dt-bindings: power: supply: axp20x_usb_power: add axp223 compatible

This adds the "x-powers,axp223-usb-power-supply" to the list of
compatibles for AXP20X VBUS power supply driver.

Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>