bnx2x: use smp_mb() to keep ordering of read write operations

Since we want to keep ordering of write to fp->bd_tx_cons and
netif_tx_queue_stopped(txq), what is read of txq->state, we have to use
general memory barrier.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bnx2x_main.c

@@ -963,7 +963,7 @@ static int bnx2x_tx_int(struct bnx2x_fastpath *fp)
 	 * start_xmit() will miss it and cause the queue to be stopped
 	 * forever.
 	 */
-	smp_wmb();
+	smp_mb();
 
 	/* TBD need a thresh? */
 	if (unlikely(netif_tx_queue_stopped(txq))) {