ARM: at91/dts: add the watchdog nodes for at91 boards

boards include:
at91sam9263ek, at91sam9g20ek, at91sam9m10g45ek, at91sam9n12ek, at91sam9x5ek

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Tested-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/arch/arm/boot/dts/at91sam9n12ek.dts b/arch/arm/boot/dts/at91sam9n12ek.dts
index 2e67cd5..d59b70c 100644
--- a/arch/arm/boot/dts/at91sam9n12ek.dts
+++ b/arch/arm/boot/dts/at91sam9n12ek.dts
@@ -77,6 +77,10 @@
 					reg = <0>;
 				};
 			};
+
+			watchdog@fffffe40 {
+				status = "okay";
+			};
 		};
 
 		nand0: nand@40000000 {