ALSA: asoc: core - add Digital Audio Interface (DAI) control functions.

This patch adds several functions for DAI control and config
and replaces the current method of calling function pointers within
the DAI struct.

Signed-off-by: Liam Girdwood <lg@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>