ath9k_htc: Fix RX URB reference count

RX URBs are automatically freed when the reference
count drops to zero - this currently doesn't happen when
usb_kill_anchored_urbs() is called during unload.

Fix this by dropping the reference count by one during
initial submission.
Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/hif_usb.c

@@ -652,6 +652,12 @@ static int ath9k_hif_usb_alloc_rx_urbs(struct hif_device_usb *hif_dev)
 			usb_unanchor_urb(urb);
 			goto err_submit;
 		}
+
+		/*
+		 * Drop reference count.
+		 * This ensures that the URB is freed when killing them.
+		 */
+		usb_free_urb(urb);
 	}
 
 	return 0;