dt-bindings: arm: cix: add OrangePi 6 Plus board

OrangePi 6 Plus adopts CIX CD8180/CD8160 SoC, built-in 12-core 64-bit
processor + NPU processor,integrated graphics processor, equipped with
16GB/32GB/64GB LPDDR5, and provides two M.2 KEY-M interfaces 2280 for NVMe
SSD,as well as SPI FLASH and TF slots to meet the needs of fast read/write
and high-capacity storage

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Gary Yang <gary.yang@cixtech.com>
Link: https://lore.kernel.org/r/20260110093406.2700505-2-gary.yang@cixtech.com
Signed-off-by: Peter Chen <peter.chen@cixtech.com>

Author: Gary Yang

Documentation/devicetree/bindings/arm/cix.yaml

@@ -16,9 +16,11 @@ properties:
   compatible:
     oneOf:
 
-      - description: Radxa Orion O6
+      - description: Sky1 based boards
         items:
-          - const: radxa,orion-o6
+          - enum:
+              - radxa,orion-o6 # Radxa Orion O6 board
+              - xunlong,orangepi-6-plus # Xunlong orangepi 6 plus board
           - const: cix,sky1
 
 additionalProperties: true