dt-bindings: hwrng: Add Amlogic Meson Hardware Random Generator bindings

Amlogic Meson Random number generator

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Required properties:

- compatible : should be "amlogic,meson-rng"

- reg : Specifies base physical address and size of the registers.

Example:

rng {

        compatible = "amlogic,meson-rng";

        reg = <0x0 0xc8834000 0x0 0x4>;

};