arm64: dts: tqma8mpql: Remove invalid/unused property

'dr_mode' is part of the USB DWC3 core, not the glue layer. Remove the
property from glue layer. Fixes the dtbs_check warning:
arch/arm64/boot/dts/freescale/imx8mp-tqma8mpql-mba8mpxl.dtb: usb@32f10108:
  'dr_mode' does not match any of the regexes: '^usb@[0-9a-f]+$',
  'pinctrl-[0-9]+'
 from schema $id: http://devicetree.org/schemas/usb/fsl,imx8mp-dwc3.yaml#Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mp-tqma8mpql-mba8mpxl.dts

@@ -602,7 +602,6 @@ &usb3_0 {
 &usb3_1 {
 	fsl,disable-port-power-control;
 	fsl,permanently-attached;
-	dr_mode = "host";
 	status = "okay";
 };