ASoC: Add Rockchip rk817 audio CODEC support

Add support for the Rockchip rk817 audio codec integrated into the
rk817 PMIC. This is based on the sources provided by Rockchip from
their BSP kernel.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Tested-by: Maciej Matuszczyk <maccraft123mc@gmail.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>