Freescale RNGA/RNGB/RNGC (Random Number Generator Versions A, B and C)

Required properties:
- compatible : should be one of
               "fsl,imx21-rnga"
               "fsl,imx31-rnga" (backward compatible with "fsl,imx21-rnga")
               "fsl,imx25-rngb"
               "fsl,imx6sl-rngb" (backward compatible with "fsl,imx25-rngb")
               "fsl,imx6sll-rngb" (backward compatible with "fsl,imx25-rngb")
               "fsl,imx6ull-rngb" (backward compatible with "fsl,imx25-rngb")
               "fsl,imx35-rngc"
- reg : offset and length of the register set of this block
- interrupts : the interrupt number for the RNG block
- clocks : the RNG clk source

Example:

rng@53fb0000 {
	compatible = "fsl,imx25-rngb";
	reg = <0x53fb0000 0x4000>;
	interrupts = <22>;
	clocks = <&trng_clk>;
};