Implement the slave_dig_outs for AD1989 cards. Untested due to lack of
hardware.
Signed-off-by: NRobin H. Johnson <robbat2@gentoo.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@perex.cz>