Freescale RNGC (Random Number Generator Version C)

The driver also supports version B, which is mostly compatible
to version C.

Required properties:
- compatible : should be one of
               "fsl,imx25-rngb"
               "fsl,imx35-rngc"
- reg : offset and length of the register set of this block
- interrupts : the interrupt number for the RNGC block
- clocks : the RNGC clk source

Example:

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