dt-bindings: rng: mediatek: add mt7986 to mtk rng binding

Add RNG binding for MT7986 SoC.
Signed-off-by: NSam Shih <sam.shih@mediatek.com>
Link: https://lore.kernel.org/r/20210726071439.14248-9-sam.shih@mediatek.comSigned-off-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/rng/mtk-rng.yaml

@@ -21,6 +21,7 @@ properties:
           - enum:
               - mediatek,mt7622-rng
               - mediatek,mt7629-rng
+              - mediatek,mt7986-rng
               - mediatek,mt8365-rng
               - mediatek,mt8516-rng
           - const: mediatek,mt7623-rng