dt-bindings: net: aspeed: add AST2700 MDIO compatible

Add "aspeed,ast2700-mdio" compatible to the binding schema with a fallback
to "aspeed,ast2600-mdio".

Although the MDIO controller on AST2700 is functionally the same as the
one on AST2600, it's good practice to add a SoC-specific compatible for
new silicon. This allows future driver updates to handle any 2700-specific
integration issues without requiring devicetree changes or complex
runtime detection logic.

For now, the driver continues to bind via the existing
"aspeed,ast2600-mdio" compatible, so no driver changes are needed.

Acked-by: Conor Dooley <[e-mail]>
Signed-off-by: Jacky Chou <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

Documentation/devicetree/bindings/net/aspeed,ast2600-mdio.yaml

···
 
 properties:
   compatible:
-    const: aspeed,ast2600-mdio
+    oneOf:
+      - const: aspeed,ast2600-mdio
+      - items:
+          - enum:
+              - aspeed,ast2700-mdio
+          - const: aspeed,ast2600-mdio
 
   reg:
     maxItems: 1