ALSA: hda - Create capture source ctls when stereo mix input is added

When the stereo mix input is explicitly enabled via a user hint, the
driver should create always a capture source enum ctl and disable the
auto-mic switch.  Otherwise the behavior gets confused.  For doing it,
this patch just sets spec->suppress_auto_mic flag appropriately.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_generic.c

@@ -3224,6 +3224,8 @@ static int create_input_ctls(struct hda_codec *codec)
 					   "Stereo Mix", 0);
 		if (err < 0)
 			return err;
+		else
+			spec->suppress_auto_mic = 1;
 	}
 
 	return 0;