dt-bindings: phy: Convert hisilicon,hi6220-usb-phy to DT schema

Convert the HiSilicon HI6220 USB PHY binding to DT schema format. It's a
straight forward conversion.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250607212524.741770-1-robh@kernel.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>