dt-bindings: net: lantiq,etop-xway: Document Lantiq Xway ETOP bindings

Document the Lantiq Xway SoC series External Bus Unit (ETOP) bindings.
Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/lantiq,etop-xway.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/lantiq,etop-xway.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Lantiq Xway ETOP Ethernet driver
+
+maintainers:
+  - John Crispin <john@phrozen.org>
+
+properties:
+  $nodename:
+    pattern: "^ethernet@[0-9a-f]+$"
+
+  compatible:
+    const: lantiq,etop-xway
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    items:
+      - description: TX interrupt
+      - description: RX interrupt
+
+  interrupt-names:
+    items:
+      - const: tx
+      - const: rx
+
+  phy-mode: true
+
+required:
+  - compatible
+  - reg
+  - interrupt-parent
+  - interrupts
+  - interrupt-names
+  - phy-mode
+
+additionalProperties: false
+
+examples:
+  - |
+    ethernet@e180000 {
+        compatible = "lantiq,etop-xway";
+        reg = <0xe180000 0x40000>;
+        interrupt-parent = <&icu0>;
+        interrupts = <73>, <78>;
+        interrupt-names = "tx", "rx";
+        phy-mode = "rmii";
+    };