ALSA: opti93x: use cs4231 lib

This patch converts the Opti93x driver to use
the cs4231 library instead of duplicating the code.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Tested-by: Rene Herman <rene.herman@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>