dt-bindings: net: renesas,etheravb: Add optional MDIO bus node

The Renesas Ethernet AVB bindings do not allow the MDIO bus to be
described. This has not been needed as only a single PHY is
supported and no MDIO bus properties have been needed.

Add an optional mdio node to the binding which allows the MDIO bus to be
described and allow bus properties to be set.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20240325153451.2366083-2-niklas.soderlund+renesas@ragnatech.se
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/renesas,etheravb.yaml

@@ -88,10 +88,16 @@ properties:
   '#address-cells':
     description: Number of address cells for the MDIO bus.
     const: 1
+    deprecated: true
 
   '#size-cells':
     description: Number of size cells on the MDIO bus.
     const: 0
+    deprecated: true
+
+  mdio:
+    $ref: /schemas/net/mdio.yaml#
+    unevaluatedProperties: false
 
   renesas,no-ether-link:
     type: boolean
@@ -110,9 +116,13 @@ properties:
   tx-internal-delay-ps:
     enum: [0, 2000]
 
+# In older bindings there where no mdio child-node to describe the MDIO bus
+# and the PHY. To not fail older bindings accept any node with an address. New
+# users should describe the PHY inside the mdio child-node.
 patternProperties:
   "@[0-9a-f]$":
     type: object
+    deprecated: true
 
 required:
   - compatible
@@ -123,8 +133,6 @@ required:
   - resets
   - phy-mode
   - phy-handle
-  - '#address-cells'
-  - '#size-cells'
 
 allOf:
   - $ref: ethernet-controller.yaml#