SiRFSoC Real Time Clock

Required properties:
- compatible: must be "sirf,prima2-sysrtc"
- reg: address range of rtc register set.
- interrupts: rtc alarm interrupts.

Example:
	rtc@2000 {
		compatible = "sirf,prima2-sysrtc";
		reg = <0x2000 0x1000>;
		interrupts = <52 53 54>;
	};