ALSA: hda/generic: Drop obsoleted obey_preferred_dacs flag

Now we evaluate directly with preferred_dacs table, the flag is no
longer used and merely a placeholder.
Let's drop the definition and its users.

Link: https://patch.msgid.link/20241001121439.26060-2-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_generic.h

@@ -232,7 +232,6 @@ struct hda_gen_spec {
 	unsigned int power_down_unused:1; /* power down unused widgets */
 	unsigned int dac_min_mute:1; /* minimal = mute for DACs */
 	unsigned int suppress_vmaster:1; /* don't create vmaster kctls */
-	unsigned int obey_preferred_dacs:1; /* obey preferred_dacs assignment */
 
 	/* other internal flags */
 	unsigned int no_analog:1; /* digital I/O only */

sound/pci/hda/patch_realtek.c

@@ -6645,10 +6645,8 @@ static void alc289_fixup_asus_ga401(struct hda_codec *codec,
 	};
 	struct alc_spec *spec = codec->spec;
 
-	if (action == HDA_FIXUP_ACT_PRE_PROBE) {
+	if (action == HDA_FIXUP_ACT_PRE_PROBE)
 		spec->gen.preferred_dacs = preferred_pairs;
-		spec->gen.obey_preferred_dacs = 1;
-	}
 }
 
 /* The DAC of NID 0x3 will introduce click/pop noise on headphones, so invalidate it */