arm: dts: mt7623: enable the usb device on the mt7623n rfb

All versions of the mt7623n RFB have an USB port so enable the device.
There is a gpio that gets used to power up the port supply. Add support
for this gpio using the fixed-regulator driver.
Signed-off-by: NJohn Crispin <john@phrozen.org>
Signed-off-by: NSean Wang <sean.wang@mediatek.com>
Signed-off-by: NMatthias Brugger <matthias.bgg@gmail.com>

arch/arm/boot/dts/mt7623n-rfb.dtsi

@@ -49,6 +49,15 @@
 		serial1 = &uart1;
 		serial2 = &uart2;
 	};
+
+	usb_p1_vbus: regulator@0 {
+		compatible = "regulator-fixed";
+		regulator-name = "usb_vbus";
+		regulator-min-microvolt = <5000000>;
+		regulator-max-microvolt = <5000000>;
+		gpio = <&pio 135 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+	};
 };
 
 &uart0 {
@@ -72,3 +81,12 @@
 	vmmc-supply = <&mt6323_vmch_reg>;
 	vqmmc-supply = <&mt6323_vmc_reg>;
 };
+
+&usb1 {
+	vbus-supply = <&usb_p1_vbus>;
+	status = "okay";
+};
+
+&u3phy1 {
+	status = "okay";
+};