ARM: dts: imx7-mba7: set dr_mode to otg on usbotg1

USBOTG1 has a Micro-USB port that can be used in host mode (using an OTG
cable) or device mode.
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx7-mba7.dtsi

@@ -579,7 +579,7 @@ &usbotg1 {
 	hnp-disable;
 	adp-disable;
 	over-current-active-low;
-	dr_mode = "host";
+	dr_mode = "otg";
 	status = "okay";
 };