ARM: dts: imx6qdl-sabresd: add dr_mode to usbotg

Currently there are 3 type of boards (imx6q|imx6qp|imx6dl-sabresd)
based on imx6qdl-sabresd.dtsi, they all do not set the dr_mode for
usbotg device node. The chipidea usb driver will configure it to otg
mode by default if the dr_mode is not set, but some testcases need to
parse the dr_mode from DT and decide the follow-up test strategy, here
set the dr_mode to otg explicitly for these 3 imx6qdl-sabresd based
boards.

Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Author: jason77-wang

arch/arm/boot/dts/nxp/imx/imx6qdl-sabresd.dtsi

@@ -804,6 +804,7 @@
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_usbotg>;
 	disable-over-current;
+	dr_mode = "otg";
 	status = "okay";
 };