underglow-layer: use behaviors to control RGBs

app/dts/bindings/behaviors/zmk,behavior-underglow-color.yaml

@@ -0,0 +1,8 @@
+# Copyright (c) 2024, The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Set underglow to specified color
+
+compatible: "zmk,behavior-underglow-color"
+
+include: one_param.yaml

app/dts/bindings/behaviors/zmk,behavior-underglow-indicators.yaml

@@ -0,0 +1,13 @@
+# Copyright (c) 2024, The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Set underglow for num lock indicator
+
+compatible: "zmk,behavior-underglow-indicators"
+
+include: two_param.yaml
+
+properties:
+  indicator:
+    type: int
+    default: 0

app/dts/bindings/zmk,underglow-layer.yaml

@@ -3,12 +3,17 @@ description: |
 
 compatible: "zmk,underglow-layer"
 
+properties:
+  pixel-lookup:
+    type: array
+    required: true
+
 child-binding:
   description: "A layer to be used in a rgbmap"
 
   properties:
     bindings:
-      type: array
+      type: phandle-array
       required: true
     layer-id:
       type: int