Update animation devicetree bindings

app/dts/bindings/animations/animation_base.yaml

@@ -0,0 +1,6 @@
+# Copyright (c) 2020, The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+pixel-cells:
+  - position_x
+  - position_y

app/dts/bindings/animations/zmk,animation-solid.yaml

@@ -6,7 +6,13 @@ description: |
 
 compatible: "zmk,animation-solid"
 
+include: animation_base.yaml
+
 properties:
+  label:
+    type: string
+    required: true
+
   duration:
     type: int
     required: true