[ALSA] ASoC: Make CPU and codec DAI operations have same type

The CPU and codec DAI operations differ only in the presence of the
digital mute operation for the codec so they may as well be the same
type.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>