ALSA: hda - Add static DAC/pin mapping for AD1986A codec

AD1986A codec is a pretty old codec and has really many hidden
restrictions.  One of such is that each DAC is dedicated to certain
pin although there are possible connections.  Currently, the generic
parser tries to assign individual DACs as much as possible, and this
lead to two bad situations: connections where the sound actually
doesn't work, and connections conflicting other channels.

We may fix this by trying to find the best connections more harder,
but as of now, it's easier to give some hints for paired DAC/pin
connections and honor them if available, since such a hint is needed
only for specific codecs (right now only AD1986A, and there will be
unlikely any others in future).

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=64971
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=66621
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_generic.h

@@ -249,6 +249,9 @@ struct hda_gen_spec {
 	const struct badness_table *main_out_badness;
 	const struct badness_table *extra_out_badness;
 
+	/* preferred pin/DAC pairs; an array of paired NIDs */
+	const hda_nid_t *preferred_dacs;
+
 	/* loopback mixing mode */
 	bool aamix_mode;