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>

arch/arm/boot/dts/at91sam9263ek.dts

@@ -89,6 +89,10 @@
 					reg = <0>;
 				};
 			};
+
+			watchdog@fffffd40 {
+				status = "okay";
+			};
 		};
 
 		nand0: nand@40000000 {

arch/arm/boot/dts/at91sam9g20ek_common.dtsi

@@ -104,6 +104,10 @@
 					reg = <1>;
 				};
 			};
+
+			watchdog@fffffd40 {
+				status = "okay";
+			};
 		};
 
 		nand0: nand@40000000 {

arch/arm/boot/dts/at91sam9m10g45ek.dts

@@ -59,6 +59,10 @@
 				status = "okay";
 			};
 
+			watchdog@fffffd40 {
+				status = "okay";
+			};
+
 			mmc0: mmc@fff80000 {
 				pinctrl-0 = <
 					&pinctrl_board_mmc0

arch/arm/boot/dts/at91sam9n12ek.dts

@@ -77,6 +77,10 @@
 					reg = <0>;
 				};
 			};
+
+			watchdog@fffffe40 {
+				status = "okay";
+			};
 		};
 
 		nand0: nand@40000000 {

arch/arm/boot/dts/at91sam9x5ek.dtsi

@@ -81,6 +81,10 @@
 					reg = <0>;
 				};
 			};
+
+			watchdog@fffffe40 {
+				status = "okay";
+			};
 		};
 
 		usb0: ohci@00600000 {