ALSA: hda - Don't touch non-existent port f on 4-port 92hd71bxx codecs

When checking for input amps on pins 0x0a, 0x0d and 0x0f, and
initializing them for 92hd71xxx codec models, we must skip nid 0x0f
for 4-port models too like with 5-port models, as it is unused
(nid 0x0f is vendor reserved in 4-port models).
Signed-off-by: NHerton Ronaldo Krzesinski <herton@mandriva.com.br>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_sigmatel.c

@@ -5072,6 +5072,8 @@ static int patch_stac92hd71bxx(struct hda_codec *codec)
 	switch (codec->vendor_id) {
 	case 0x111d76b6: /* 4 Port without Analog Mixer */
 	case 0x111d76b7:
+		unmute_init++;
+		/* fallthru */
 	case 0x111d76b4: /* 6 Port without Analog Mixer */
 	case 0x111d76b5:
 		memcpy(&spec->private_dimux, &stac92hd71bxx_dmux_nomixer,