dt-bindings: net: brcm,iproc-mdio: convert to the json-schema

This helps validating DTS files.

Introduced changes:
1. Swapped #address-cells and #size-cells values
2. Renamed node: s/enet-gphy/ethernet-phy@/
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/brcm,iproc-mdio.txt

-* Broadcom iProc MDIO bus controller
-
-Required properties:
-- compatible: should be "brcm,iproc-mdio"
-- reg: address and length of the register set for the MDIO interface
-- #size-cells: must be 1
-- #address-cells: must be 0
-
-Child nodes of this MDIO bus controller node are standard Ethernet PHY device
-nodes as described in Documentation/devicetree/bindings/net/phy.txt
-
-Example:
-
-mdio@18002000 {
-	compatible = "brcm,iproc-mdio";
-	reg = <0x18002000 0x8>;
-	#size-cells = <1>;
-	#address-cells = <0>;
-
-	enet-gphy@0 {
-		reg = <0>;
-	};
-};

Documentation/devicetree/bindings/net/brcm,iproc-mdio.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/brcm,iproc-mdio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom iProc MDIO bus controller
+
+maintainers:
+  - Rafał Miłecki <rafal@milecki.pl>
+
+allOf:
+  - $ref: mdio.yaml#
+
+properties:
+  compatible:
+    const: brcm,iproc-mdio
+
+  reg:
+    maxItems: 1
+
+unevaluatedProperties: false
+
+required:
+  - reg
+
+examples:
+  - |
+    mdio@18002000 {
+        compatible = "brcm,iproc-mdio";
+        reg = <0x18002000 0x8>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ethernet-phy@0 {
+            reg = <0>;
+        };
+    };