ASoC: add driver for Rockchip RK3xxx I2S controller

Add driver for i2s controller found on rk3066, rk3168 and rk3288
processors from rockchip.

Tested on the RK3288 SDK board.

Signed-off-by: Jianqun Xu <xjq@rock-chips.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
6 files changed