ASoC: rockchip: add bindings for i2s

This patch add bindings for rk3036/rk3228/rk3328/rk3366 i2s.
Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

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

@@ -7,8 +7,12 @@ Required properties:
 
 - compatible: should be one of the following:
    - "rockchip,rk3066-i2s": for rk3066
+   - "rockchip,rk3036-i2s", "rockchip,rk3066-i2s": for rk3036
    - "rockchip,rk3188-i2s", "rockchip,rk3066-i2s": for rk3188
+   - "rockchip,rk3228-i2s", "rockchip,rk3066-i2s": for rk3228
    - "rockchip,rk3288-i2s", "rockchip,rk3066-i2s": for rk3288
+   - "rockchip,rk3328-i2s", "rockchip,rk3066-i2s": for rk3328
+   - "rockchip,rk3366-i2s", "rockchip,rk3066-i2s": for rk3366
    - "rockchip,rk3368-i2s", "rockchip,rk3066-i2s": for rk3368
    - "rockchip,rk3399-i2s", "rockchip,rk3066-i2s": for rk3399
 - reg: physical base address of the controller and length of memory mapped