siflower: sf21: fix usb_vbus for Bananapi BPI-RV2

Add usb_vbus ref to usb device.

Signed-off-by: Andrey Safonov <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/19698
Signed-off-by: Robert Marko <[email protected]>

target/linux/siflower/dts/sf21h8898_bananapi_bpi-rv2.dtsi

@@ -194,6 +194,7 @@
 };
 
 &usb {
+	vbus-supply = <&usb_vbus>;
 	status = "okay";
 };