dt-bindings: usb: amlogic,meson-g12a-usb-ctrl: make G12A usb3-phy0 optional

dt-bindings: usb: amlogic,meson-g12a-usb-ctrl: make G12A usb3-phy0 optional

On the G12A USB complex, the USB3 PHY is shared with the PCIe controller,
thus on designs without PCIe enabled the USB3 PHY entry can be ommited from
the PHY list.

Fixes: cdff2c946f06 ("dt-bindings: usb: amlogic,meson-g12a-usb-ctrl: add the Amlogic AXG Families USB Glue Bindings")
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230207-b4-amlogic-g12a-usb-ctrl-bindings-fix-v1-1-c310293da7a2@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>