[ALSA] ac97 - Fix vt1617a build ops

This patch connects the extra vt1616 controls for the vt1617a, which
is necessary to control the rear speakers on e.g. a Shuttle SN25P.

Signed-off-by: Daniel Jacobowitz <drow@false.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>