dt-bindings: arm: Add compatible for Mediatek MT8192

This commit adds dt-binding documentation for the Mediatek MT8192
reference board.
Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
Link: https://lore.kernel.org/r/20220419092030.30519-1-allen-kh.cheng@mediatek.comSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>

Documentation/devicetree/bindings/arm/mediatek.yaml

@@ -131,6 +131,10 @@ properties:
           - enum:
               - mediatek,mt8183-evb
           - const: mediatek,mt8183
+      - items:
+          - enum:
+              - mediatek,mt8192-evb
+          - const: mediatek,mt8192
       - items:
           - enum:
               - mediatek,mt8195-evb