[ALSA] ASoC codecs: generic AC97 support

This patch allows the std Alsa AC97 codec driver to use any AsoC AC97
controller driver. Currently, only HiFi playback and Capture are
supported atm.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>