dt-bindings: net: Document QCA808x PHYs

Add Documentation for QCA808x PHYs for the additional LED configuration
for this PHY.

Signed-off-by: Christian Marangi <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/devicetree/bindings/net/qca,qca808x.yaml

···
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/qca,qca808x.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Atheros QCA808X PHY
+
+maintainers:
+  - Christian Marangi <[e-mail]>
+
+description:
+  QCA808X PHYs can have up to 3 LEDs attached.
+  All 3 LEDs are disabled by default.
+  2 LEDs have dedicated pins with the 3rd LED having the
+  double function of Interrupt LEDs/GPIO or additional LED.
+
+  By default this special PIN is set to LED function.
+
+allOf:
+  - $ref: ethernet-phy.yaml#
+
+properties:
+  compatible:
+    enum:
+      - ethernet-phy-id004d.d101
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/leds/common.h>
+
+    mdio {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ethernet-phy@0 {
+            compatible = "ethernet-phy-id004d.d101";
+            reg = <0>;
+
+            leds {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                led@0 {
+                    reg = <0>;
+                    color = <LED_COLOR_ID_GREEN>;
+                    function = LED_FUNCTION_WAN;
+                    default-state = "keep";
+                };
+            };
+        };
+    };