ALSA: hda - Remove non-working headphone control for Dell laptops

The previous commit re-enabled hp_nid setup for IDT92HD73*, but
it's unneeded indeed for Dell laptops that have multiple headphones.
Setting the extra hp_nid results in a non-working "Headpohne" mixer
control.  Thus hp_nid should be 0 for these dell models.

Also, the automatic addition of hp_nid should check whether it's
a dual-HP model or not.  For dual-HPs, the pins are already checked
by the early workaround.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_sigmatel.c

@@ -2903,7 +2903,7 @@ static int stac92xx_auto_create_multi_out_ctls(struct hda_codec *codec,
 	}
 
 	if ((spec->multiout.num_dacs - cfg->line_outs) > 0 &&
-			cfg->hp_outs && !spec->multiout.hp_nid)
+	    cfg->hp_outs == 1 && !spec->multiout.hp_nid)
 		spec->multiout.hp_nid = nid;
 
 	if (cfg->hp_outs > 1 && cfg->line_out_type == AUTO_PIN_LINE_OUT) {
@@ -4307,6 +4307,7 @@ static int patch_stac92hd73xx(struct hda_codec *codec)
 		spec->amp_nids = &stac92hd73xx_amp_nids[DELL_M6_AMP];
 		spec->eapd_switch = 0;
 		spec->num_amps = 1;
+		spec->multiout.hp_nid = 0; /* dual HPs */
 
 		if (!spec->init)
 			spec->init = dell_m6_core_init;