Exynos Pseudo Random Number Generator

Required properties:

- compatible  : One of:
                - "samsung,exynos4-rng" for Exynos4210 and Exynos4412
                - "samsung,exynos5250-prng" for Exynos5250+
- reg         : Specifies base physical address and size of the registers map.
- clocks      : Phandle to clock-controller plus clock-specifier pair.
- clock-names : "secss" as a clock name.

Example:

	rng@10830400 {
		compatible = "samsung,exynos4-rng";
		reg = <0x10830400 0x200>;
		clocks = <&clock CLK_SSS>;
		clock-names = "secss";
	};