arm: dts: Enable support for USB on XEA (imx28) board

This change enables the support for USB with DM on the XEA (imx28)
board.

Signed-off-by: Lukasz Majewski <lukma@denx.de>

arch/arm/dts/imx28-xea.dts

@@ -41,6 +41,15 @@
 		enable-active-high;
 		regulator-boot-on;
 	};
+
+	reg_usb_5v: regulator-usb-5v {
+		compatible = "regulator-fixed";
+		regulator-name = "usb_vbus";
+		regulator-min-microvolt = <5000000>;
+		regulator-max-microvolt = <5000000>;
+		gpio = <&gpio1 28 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+	};
 };
 
 &mac0 {
@@ -123,3 +132,12 @@
 		};
 	};
 };
+
+&usb0 {
+	vbus-supply = <&reg_usb_5v>;
+	status = "okay";
+};
+
+&usbphy0 {
+	status = "okay";
+};