ARM: dts: imx6ul-14x14-evk: add USB dual-role support

With commit 851ce932 ("usb: chipidea: otg: don't wait vbus
drops below BSV when starts host"), the driver can support
enabling vbus output without software control, so this board
(control vbus output through ID pin) can support dual-role now.
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6ul-14x14-evk.dts

@@ -225,7 +225,7 @@ &uart2 {
 };
 
 &usbotg1 {
-	dr_mode = "peripheral";
+	dr_mode = "otg";
 	status = "okay";
 };