Add a binding for a behavior with a third parameter

app/dts/bindings/behaviors/three_param.yaml

@@ -0,0 +1,17 @@
+# Copyright (c) 2020 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+properties:
+  label:
+    type: string
+    required: false
+    deprecated: true
+  "#binding-cells":
+    type: int
+    required: true
+    const: 3
+
+binding-cells:
+  - param1
+  - param2
+  - param3