dt-bindings: arm: Add compatible for MediaTek MT8188

This commit adds dt-binding documentation for the MediaTek MT8188
reference board.
Signed-off-by: jason-ch chen <Jason-ch.Chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231023083839.24453-2-jason-ch.chen@mediatek.comSigned-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Documentation/devicetree/bindings/arm/mediatek.yaml

@@ -174,6 +174,10 @@ properties:
           - enum:
               - mediatek,mt8186-evb
           - const: mediatek,mt8186
+      - items:
+          - enum:
+              - mediatek,mt8188-evb
+          - const: mediatek,mt8188
       - items:
           - enum:
               - mediatek,mt8192-evb