rt2x00: rt2800pci: use rt2x00dev->tx->limit

The TX data queue is initialized already when
the rt2800pci_txstatus_interrupt() function is
called.

Fetch the number of the queue entries from that
instead of using the entry_num field of the data
queue descriptor.

The two values are the same, and the use of the
rt2x00dev->tx->limit value allows us to get rid
of a superfluous pointer dereference.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2800pci.c

@@ -1014,7 +1014,7 @@ static void rt2800pci_txstatus_interrupt(struct rt2x00_dev *rt2x00dev)
 	 * Since we have only one producer and one consumer we don't
 	 * need to lock the kfifo.
 	 */
-	for (i = 0; i < rt2x00dev->ops->tx->entry_num; i++) {
+	for (i = 0; i < rt2x00dev->tx->limit; i++) {
 		rt2x00mmio_register_read(rt2x00dev, TX_STA_FIFO, &status);
 
 		if (!rt2x00_get_field32(status, TX_STA_FIFO_VALID))