ARM: at91: enable USB host on at91sam9n12ek board

Enable USB host on at91sam9n12ek board.
Signed-off-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/boot/dts/at91sam9n12ek.dts

@@ -124,6 +124,10 @@ nand0: nand@40000000 {
 			nand-on-flash-bbt;
 			status = "okay";
 		};
+
+		usb0: ohci@00500000 {
+			status = "okay";
+		};
 	};
 
 	leds {