dt-bindings: ASoC: rockchip: Add compatible for RK3128 spdif

Add compatible for RK3128's S/PDIF.
Signed-off-by: Alex Bee <knaerzche@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230829171647.187787-4-knaerzche@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/rockchip-spdif.yaml

@@ -26,6 +26,7 @@ properties:
       - const: rockchip,rk3568-spdif
       - items:
           - enum:
+              - rockchip,rk3128-spdif
               - rockchip,rk3188-spdif
               - rockchip,rk3288-spdif
               - rockchip,rk3308-spdif