dt-bindings: arm: rockchip: Add ArmSoM Sige7

Add devicetree binding for ArmSoM Sige7 board
Signed-off-by: Jianfeng Liu <liujianfeng1994@gmail.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Weizhao Ouyang <weizhao.ouyang@arm.com>
Link: https://lore.kernel.org/r/20240420034300.176920-3-liujianfeng1994@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -49,6 +49,11 @@ properties:
               - anbernic,rg-arc-s
           - const: rockchip,rk3566
 
+      - description: ArmSoM Sige7 board
+        items:
+          - const: armsom,sige7
+          - const: rockchip,rk3588
+
       - description: Asus Tinker board
         items:
           - const: asus,rk3288-tinker