dt-bindings: net: dsa: mediatek,mt7530: add dsa-port definition for mt7988

Add own dsa-port binding for SoC with internal switch where only phy-mode
'internal' is valid.

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patch.msgid.link/20250709111147.11843-6-linux@fw-web.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml

@@ -190,6 +190,18 @@ required:
   - reg
 
 $defs:
+  builtin-dsa-port:
+    patternProperties:
+      "^(ethernet-)?ports$":
+        patternProperties:
+          "^(ethernet-)?port@[0-6]$":
+            if:
+              required: [ ethernet ]
+            then:
+              properties:
+                phy-mode:
+                  const: internal
+
   mt7530-dsa-port:
     patternProperties:
       "^(ethernet-)?ports$":
@@ -297,7 +309,7 @@ allOf:
             - airoha,en7581-switch
             - airoha,an7583-switch
     then:
-      $ref: "#/$defs/mt7530-dsa-port"
+      $ref: "#/$defs/builtin-dsa-port"
       properties:
         gpio-controller: false
         mediatek,mcm: false