pitx-imx8m: fix dts merge error

- During merge to imx_v2020.04_5.4.24_2.1.0 branch the '&usb_dwc3_1'
  node reference was duplicated in the pitx-imx8m device tree. As a
  result, USB port 1 support was broken. Fix this and remove superfluous
  usb_dwc3_1 reference.
Signed-off-by: Thomas Schaefer <thomas.schaefer@kontron.com>

arch/arm/dts/pitx-imx8mq.dts

@@ -493,12 +493,6 @@
 	status = "okay";
 };
 
-&usb_dwc3_1 {
-	compatible = "fsl, imx8mq-dwc3";
-	status = "okay";
-	dr_mode = "host";
-};
-
 &wdog1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_wdog>;