dt-bindings: arm: rockchip: Add Radxa ROCK S0

Add devicetree binding for the Radxa ROCK S0 board.

Radxa ROCK S0 is a single-board computer based on the Rockchip RK3308B
SoC in an ultra-compact form factor.
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240521212247.1240226-2-jonas@kwiboo.seSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -814,6 +814,11 @@ properties:
           - const: radxa,rock-5b
           - const: rockchip,rk3588
 
+      - description: Radxa ROCK S0
+        items:
+          - const: radxa,rock-s0
+          - const: rockchip,rk3308
+
       - description: Radxa ZERO 3W/3E
         items:
           - enum: