dt-bindings: reset: add BCM6345 reset controller bindings

Add device tree binding documentation for BCM6345 reset controller.
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

Documentation/devicetree/bindings/reset/brcm,bcm6345-reset.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/reset/brcm,bcm6345-reset.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: BCM6345 reset controller
+
+description: This document describes the BCM6345 reset controller.
+
+maintainers:
+  - Álvaro Fernández Rojas <noltari@gmail.com>
+
+properties:
+  compatible:
+    const: brcm,bcm6345-reset
+
+  reg:
+    maxItems: 1
+
+  "#reset-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - "#reset-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    reset-controller@10000010 {
+      compatible = "brcm,bcm6345-reset";
+      reg = <0x10000010 0x4>;
+      #reset-cells = <1>;
+    };