ARM: dts: am57xx-beagle-x15: Fix USB2 mode

On this board USB2 is meant to be used as peripheral only.
The ID pin for USB2 is hardwired HIGH.
Signed-off-by: NRoger Quadros <rogerq@ti.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am57xx-beagle-x15.dts

@@ -556,3 +556,7 @@
 &omap_dwc3_2 {
 	extcon = <&extcon_usb2>;
 };
+
+&usb2 {
+	dr_mode = "peripheral";
+};