ALSA: usx2y: remove an unneeded check

The test here is always true because S[i].urb is an array not a pointer.
Also it's bogus because the intent was to test:
	if (S->urb[i]) {
instead of:
	if (S[i].urb) {

Anyway, usb_kill_urb() and usb_free_urb() accept NULL pointers so we can
just remove this.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/usx2y/usbusx2y.c

@@ -305,12 +305,10 @@ static void usX2Y_unlinkSeq(struct snd_usX2Y_AsyncSeq *S)
 {
 	int	i;
 	for (i = 0; i < URBS_AsyncSeq; ++i) {
-		if (S[i].urb) {
 		usb_kill_urb(S->urb[i]);
 		usb_free_urb(S->urb[i]);
 		S->urb[i] = NULL;
 	}
-	}
 	kfree(S->buffer);
 }