ARM: dts: Enable RTC node for Arndale

The issues reported in commit 522ccdb6 ("ARM: dts: Disable the RTC
by default on exynos5") are no longer reproduced on EXYNOS5250 based
Arndale board. Hence re-enabling RTC support for Arndale board.

This is helpful for testing S2R on Arndale board.
Signed-off-by: NTushar Behera <tushar.behera@linaro.org>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>

arch/arm/boot/dts/exynos5250-arndale.dts

@@ -477,4 +477,7 @@
 		};
 	};
 
+	rtc {
+		status = "okay";
+	};
 };