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

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

Documentation/devicetree/bindings/rng/amlogic,meson-rng.txt

+Amlogic Meson Random number generator
+=====================================
+
+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>;
+};