arm64: dts: Add RTC DTS entry for X-Gene v2 SoC platform

Add Dallas DS1337 RTC DTS entry to support RTC function
on X-Gene v2 evaluation platform.

Signed-off-by: Duc Dang <dhdang@apm.com>

arch/arm64/boot/dts/apm/apm-merlin.dts

@@ -74,3 +74,11 @@
 &mmc0 {
 	status = "ok";
 };
+
+&i2c4 {
+	rtc68: rtc@68 {
+		compatible = "dallas,ds1337";
+		reg = <0x68>;
+		status = "ok";
+	};
+};