ARM: at91/dt: at91sam9x5cm: enable RTC

Enable RTC for all the at91sam9x5 CPU Modules: this will enable it for all the
EK boards.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/boot/dts/at91sam9x5cm.dtsi

@@ -42,6 +42,10 @@
 					};
 				};
 			};
+
+			rtc@fffffeb0 {
+				status = "okay";
+			};
 		};
 
 		nand0: nand@40000000 {