dt-bindings: arm: rockchip: Add Relfor Saib board

Add devicetree binding for the Relfor saib board which
is based on Rockchip RV1109

Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Karthikeyan Krishnasamy <karthikeyan@linumiz.com>
Link: https://lore.kernel.org/r/20240912142451.2952633-6-karthikeyan@linumiz.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Author: karthi012

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -884,6 +884,11 @@ properties:
               - radxa,zero-3w
           - const: rockchip,rk3566
 
+      - description: Relfor SAIB board
+        items:
+          - const: relfor,saib
+          - const: rockchip,rv1109
+
       - description: Rikomagic MK808 v1
         items:
           - const: rikomagic,mk808