ARM: dts: imx6sl-warp: Fix OTG roles

USBOTG1 always work on peripheral mode and USBOTG in host mode, so fix
their roles accordingly.

Tested by mounting the MMC card as a storage device:

modprobe g_mass_storage file=/dev/mmcblk0p2
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Acked-by: NOtavio Salvador <otavio@ossystems.com.br>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx6sl-warp.dts

@@ -87,12 +87,13 @@
 };
 
 &usbotg1 {
-	dr_mode = "host";
+	dr_mode = "peripheral";
 	disable-over-current;
 	status = "okay";
 };
 
 &usbotg2 {
+	dr_mode = "host";
 	disable-over-current;
 	status = "okay";
 };