ALSA: usb-audio: Proper fallback at get_term_name()

get_term_name() calls snd_usb_copy_string_desc() for retrieving the
name when a specific ID (name field) is given.  When this returns an
error (zero), however, it simply returns as is.  This will end up in a
fixed name string in the caller side, which often is meaningless.

For giving a bit more useful name string depending on the terminal
type, change the get_term_name() function to go through the fallback
mode.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/mixer.c

@@ -656,10 +656,14 @@ static int get_term_name(struct mixer_build *state, struct usb_audio_term *iterm
 			 unsigned char *name, int maxlen, int term_only)
 {
 	struct iterm_name_combo *names;
+	int len;
 
-	if (iterm->name)
-		return snd_usb_copy_string_desc(state, iterm->name,
+	if (iterm->name) {
+		len = snd_usb_copy_string_desc(state, iterm->name,
 						name, maxlen);
+		if (len)
+			return len;
+	}
 
 	/* virtual type - not a real terminal */
 	if (iterm->type >> 16) {