mfd: Add Rockchip rk817 audio CODEC support

Add rk817 codec support cell to rk808 mfd driver.

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