[ALSA] ac97 - Smart 5.1 for VIA 1617a codec

This patch provides a single 8 way enum called 'Smart 5.1 Select' with
some reasonable names for each enum that allows the user to choose
which of the 8 possible settings for vt1617a's version of what via
calls 'Smart 5.1'.

Signed-off-by: John Utz <john.utz@dmx.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>