dts: imx6ull: add USB aliases to support DM

Signed-off-by: Filip Brozovic <fbrozovic@gmail.com>
diff --git a/arch/arm/dts/imx6ull.dtsi b/arch/arm/dts/imx6ull.dtsi
index 97236d8..4598f2f 100644
--- a/arch/arm/dts/imx6ull.dtsi
+++ b/arch/arm/dts/imx6ull.dtsi
@@ -46,6 +46,8 @@
 		spi4 = &ecspi4;
 		usbphy0 = &usbphy1;
 		usbphy1 = &usbphy2;
+		usb0 = &usbotg1;
+		usb1 = &usbotg2;
 	};
 
 	cpus {