ALSA: usx2y: fix a double free bug

In usX2Y_In04_init(), a new urb is firstly created through usb_alloc_urb()
and saved to 'usX2Y->In04urb'. Then, a buffer is allocated through
kmalloc() and saved to 'usX2Y->In04Buf'. If the allocation of the buffer
fails, the error code ENOMEM is returned after usb_free_urb(), which frees
the created urb. However, the urb is actually freed at card->private_free
callback, i.e., snd_usX2Y_card_private_free(). So the free operation here
leads to a double free bug.

To fix the above issue, simply remove usb_free_urb().

Signed-off-by: Wenwen Wang <wang6495@umn.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/usx2y/usbusx2y.c

@@ -293,10 +293,8 @@ int usX2Y_In04_init(struct usX2Ydev *usX2Y)
 	if (! (usX2Y->In04urb = usb_alloc_urb(0, GFP_KERNEL)))
 		return -ENOMEM;
 
-	if (! (usX2Y->In04Buf = kmalloc(21, GFP_KERNEL))) {
-		usb_free_urb(usX2Y->In04urb);
+	if (! (usX2Y->In04Buf = kmalloc(21, GFP_KERNEL)))
 		return -ENOMEM;
-	}
 
 	init_waitqueue_head(&usX2Y->In04WaitQueue);
 	usb_fill_int_urb(usX2Y->In04urb, usX2Y->dev, usb_rcvintpipe(usX2Y->dev, 0x4),