phy: stm32-usbphyc: use connector for vbus-supply with phy-stm32-usbphyc

The vbus-supply is an optional property of sub-node connector node.
and no more in the usb phyc node (in first proposed binding).

This regulator for USB VBUS may be needed for host mode.

See the latest kernel binding for details in
Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml.

  usbphyc_port0: usb-phy@0 {
      reg = <0>;
      phy-supply = <&vdd_usb>;
      #phy-cells = <0>;
      connector {
          compatible = "usb-a-connector";
          vbus-supply = <&vbus_sw>;
      };
  };

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>