ASoC: dt-bindings: rockchip: Add compatible for RK3588

Add new compatible string for the Rockchip I2S/PCM controller found on
RK3588 and RK3588S SoCs.
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Link: https://lore.kernel.org/r/20230315114806.3819515-8-cristian.ciocaltea@collabora.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/rockchip-i2s.yaml

@@ -34,6 +34,7 @@ properties:
               - rockchip,rk3366-i2s
               - rockchip,rk3368-i2s
               - rockchip,rk3399-i2s
+              - rockchip,rk3588-i2s
               - rockchip,rv1126-i2s
           - const: rockchip,rk3066-i2s