ARM: dts: imx53-qsb: Allow usb peripheral mode to work

Trying to use the usb otg port on mx53qsb results in the following error:

$ modprobe g_ether
using random self ethernet address
using random host ethernet address
usb0: HOST MAC 52:0f:8a:1e:aa:09
usb0: MAC de:f3:70:d8:6c:62
using random self ethernet address
using random host ethernet address
g_ether gadget: Ethernet Gadget, version: Memorial Day 2008
g_ether gadget: g_ether ready

(Connect the USB cable)

$ ci_hdrc ci_hdrc.0: remove, state 4
usb usb1: USB disconnect, device number 1
ci_hdrc ci_hdrc.0: USB bus 1 deregistered
ci_hdrc ci_hdrc.0: timeout waiting for 00000800 in 11

USB otg port goes to connector J3 (mini USB) and also to the USB combo (J2).

As mx53qsb does not provide a USB ID pin, pass the dr_mode as 'peripheral' so
that we can have usb device working.

Tested via g_ether.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx53-qsb.dts

@@ -318,5 +318,6 @@ &usbh1 {
 };
 
 &usbotg {
+	dr_mode = "peripheral";
 	status = "okay";
 };