dt-bindings: arm: Convert Conexant Digicolor board/soc bindings to json-schema

Convert Conexant Digicolor SoC bindings to DT schema format using json-schema.
Acked-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/digicolor.txt

-Conexant Digicolor Platforms Device Tree Bindings
-
-Each device tree must specify which Conexant Digicolor SoC it uses.
-Must be the following compatible string:
-
-  cnxt,cx92755

Documentation/devicetree/bindings/arm/digicolor.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/digicolor.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Conexant Digicolor Platforms Device Tree Bindings
+
+maintainers:
+  - Baruch Siach <baruch@tkos.co.il>
+
+properties:
+  compatible:
+    const: cnxt,cx92755
+
+...