dt-bindings: arm: add CIX P1 (SKY1) SoC

Add device tree bindings for CIX P1 (Internal name sky1) Arm SoC,
it consists several SoC models like CP8180, CD8180, etc.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Fugang Duan <fugang.duan@cixtech.com>
Signed-off-by: Peter Chen <peter.chen@cixtech.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Documentation/devicetree/bindings/arm/cix.yaml

@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/cix.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: CIX platforms
+
+maintainers:
+  - Peter Chen <peter.chen@cixtech.com>
+  - Fugang Duan <fugang.duan@cixtech.com>
+
+properties:
+  $nodename:
+    const: '/'
+  compatible:
+    oneOf:
+
+      - description: Radxa Orion O6
+        items:
+          - const: radxa,orion-o6
+          - const: cix,sky1
+
+additionalProperties: true
+
+...