ALSA: hda - Fix error check from snd_hda_get_conn_index() in patch_cirrus.c

snd_hda_get_conn_index() returns a negative value while the current code
stores it in an unsigned int.  It must be stored in a signed integer.
Reported-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_cirrus.c

@@ -375,7 +375,7 @@ static int is_ext_mic(struct hda_codec *codec, unsigned int idx)
 static hda_nid_t get_adc(struct hda_codec *codec, hda_nid_t pin,
 			 unsigned int *idxp)
 {
-	int i;
+	int i, idx;
 	hda_nid_t nid;
 
 	nid = codec->start_nid;
@@ -384,9 +384,11 @@ static hda_nid_t get_adc(struct hda_codec *codec, hda_nid_t pin,
 		type = get_wcaps_type(get_wcaps(codec, nid));
 		if (type != AC_WID_AUD_IN)
 			continue;
-		*idxp = snd_hda_get_conn_index(codec, nid, pin, false);
-		if (*idxp >= 0)
+		idx = snd_hda_get_conn_index(codec, nid, pin, false);
+		if (idx >= 0) {
+			*idxp = idx;
 			return nid;
+		}
 	}
 	return 0;
 }