ARM: dts: Enable S3C RTC on exynos4412-trats2 and exynos5420-arndale-octa

Extend the S3C RTC node with rtc_src clock so it could be operational.
The rtc_src clock is provided by MAX77686 (Trats2) or S2MPS11 (Arndale
Octa).

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Kukjin Kim <kgene@kernel.org>
diff --git a/arch/arm/boot/dts/exynos4.dtsi b/arch/arm/boot/dts/exynos4.dtsi
index e20cdc2..76929d3 100644
--- a/arch/arm/boot/dts/exynos4.dtsi
+++ b/arch/arm/boot/dts/exynos4.dtsi
@@ -266,7 +266,7 @@
 		status = "disabled";
 	};
 
-	rtc@10070000 {
+	rtc: rtc@10070000 {
 		compatible = "samsung,s3c6410-rtc";
 		reg = <0x10070000 0x100>;
 		interrupt-parent = <&pmu_system_controller>;