APM X-Gene SoC random number generator.

Required properties:

- compatible  : should be "apm,xgene-rng"
- reg         : specifies base physical address and size of the registers map
- clocks      : phandle to clock-controller plus clock-specifier pair
- interrupts  : specify the fault interrupt for the RNG device

Example:

	rng: rng@10520000 {
		compatible = "apm,xgene-rng";
		reg = <0x0 0x10520000 0x0 0x100>;
		interrupts =   <0x0 0x41 0x4>;
		clocks = <&rngpkaclk 0>;
	};