* APM X-Gene Real Time Clock

RTC controller for the APM X-Gene Real Time Clock

Required properties:
- compatible : Should be "apm,xgene-rtc"
- reg: physical base address of the controller and length of memory mapped
  region.
- interrupts: IRQ line for the RTC.
- #clock-cells: Should be 1.
- clocks: Reference to the clock entry.

Optional properties:
- prescaler: Reference to the Value of Counter Prescaler.

Example:

rtcclk: rtcclk {
	compatible = "fixed-clock";
	#clock-cells = <1>;
	clock-frequency = <100000000>;
	clock-output-names = "rtcclk";
};

rtc: rtc@10510000 {
	compatible = "apm,xgene-rtc";
	reg = <0x0 0x10510000 0x0 0x400>;
	interrupts = <0x0 0x46 0x4>;
	#clock-cells = <1>;
	clocks = <&rtcclk 0>;
};

Example XuanTie TH1520 RTC node with Counter Prescaler(prescaler):

rtc: rtc@fffff40000 {
	compatible = "snps,dw-apb-rtc";
	reg = <0xff 0xfff40000 0x0 0x1000>;
	interrupts = <74 IRQ_TYPE_LEVEL_HIGH>;
	clocks = <&osc_32k>;
	clock-names = "osc_32k";
	wakeup-source;
	prescaler = <0x8000>;
	status = "okay";
};
