dt-bindings: arm64: mediatek: add mt8390-evk board

1. Add compatible for MT8390.
2. Add bindings for the MediaTek mt8390-evk board, also known
as the "Genio 700-EVK".

The MT8390 and MT8188 belong to the same SoC family,
with only minor differences in their physical characteristics.
They utilize unique efuse values for differentiation.

The booting process and configurations are managed by boot
loaders, firmware, and TF-A. Consequently, the part numbers
and procurement channels vary.
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230915081212.13959-1-macpaul.lin@mediatek.comSigned-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Documentation/devicetree/bindings/arm/mediatek.yaml

@@ -352,6 +352,11 @@ properties:
           - enum:
               - mediatek,mt8365-evk
           - const: mediatek,mt8365
+      - items:
+          - enum:
+              - mediatek,mt8390-evk
+          - const: mediatek,mt8390
+          - const: mediatek,mt8188
       - items:
           - enum:
               - mediatek,mt8395-evk