dt-bindings: arm: rockchip: Add Firefly Station M2

The Station M2 is a compact single board computer based on the rk3566
SoC. It outputs on uart2 for debug and console purposes.
Signed-off-by: Peter Geis <pgwipeout@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220429115252.2360496-4-pgwipeout@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -133,6 +133,11 @@ properties:
               - firefly,roc-rk3399-pc-plus
           - const: rockchip,rk3399
 
+      - description: Firefly Station M2
+        items:
+          - const: firefly,rk3566-roc-pc
+          - const: rockchip,rk3566
+
       - description: FriendlyElec NanoPi R2S
         items:
           - const: friendlyarm,nanopi-r2s