ASoC: rockchip: add bindings for rk3399 i2s

Add devicetree bindings for i2s controller found on rk3399
processors from rockchip.

It's helpful to add full set of compatible strings for serials
of Rockchip SoCs (rk3066, rk3188, rk3288, rk3399).
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NJianqun Xu <jay.xu@rock-chips.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

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

@@ -9,6 +9,7 @@ Required properties:
    - "rockchip,rk3066-i2s": for rk3066
    - "rockchip,rk3188-i2s", "rockchip,rk3066-i2s": for rk3188
    - "rockchip,rk3288-i2s", "rockchip,rk3066-i2s": for rk3288
+   - "rockchip,rk3399-i2s", "rockchip,rk3066-i2s": for rk3399
 - reg: physical base address of the controller and length of memory mapped
   region.
 - interrupts: should contain the I2S interrupt.

sound/soc/rockchip/rockchip_i2s.c

@@ -575,6 +575,9 @@ static int rockchip_i2s_remove(struct platform_device *pdev)
 
 static const struct of_device_id rockchip_i2s_match[] = {
 	{ .compatible = "rockchip,rk3066-i2s", },
+	{ .compatible = "rockchip,rk3188-i2s", },
+	{ .compatible = "rockchip,rk3288-i2s", },
+	{ .compatible = "rockchip,rk3399-i2s", },
 	{},
 };