ARM: dts: Enable RTC node for exynos5250-snow

By default the exynos RTC is disabled.  Enable it for snow.  There's
also an external RTC on the max77686 PMIC but we haven't yet enabled
that.
Signed-off-by: NDoug Anderson <dianders@chromium.org>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>

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

@@ -171,6 +171,10 @@
 		};
 	};
 
+	rtc {
+		status = "okay";
+	};
+
 	/*
 	 * On Snow we've got SIP WiFi and so can keep drive strengths low to
 	 * reduce EMI.