ALSA: jack: Fix endless loop at unique index detection

While the commit [d0a601c278de: ALSA: jack: Fix the id uniqueness
check] fixes the wrong string check, it leads to a worse result -- the
loop in get_available_index() goes into an endless loop.  The cause is
that snd_ctl_find_id() returns the object assigned to the numid if
it's set.  Thus it points to the previous entry again.

This patch clears the numid field for the next call properly.

Reported-and-tested-by: Tomáš Pružina <pruzinat@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/ctljack.c

@@ -41,8 +41,11 @@ static int get_available_index(struct snd_card *card, const char *name)
 	sid.iface = SNDRV_CTL_ELEM_IFACE_CARD;
 	strlcpy(sid.name, name, sizeof(sid.name));
 
-	while (snd_ctl_find_id(card, &sid))
+	while (snd_ctl_find_id(card, &sid)) {
 		sid.index++;
+		/* reset numid; otherwise snd_ctl_find_id() hits this again */
+		sid.numid = 0;
+	}
 
 	return sid.index;
 }