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.com


Signed-off-by: Mark Brown <broonie@kernel.org>