net/mlx4_en: Disable global flow control when PFC enabled

Fix a bug when FC and PFC are enabled/disabled at the same time.
According to ConnectX-3 Programmer Manual these two features are mutial
exclusive.  So make sure when enabling PFC to turn off global FC and
vise versa.  Otherwise it hurts the performance.
Signed-off-by: NEugenia Emantayev <eugenia@mellanox.com>
Signed-off-by: NAmir Vadai <amirv@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_dcb_nl.c

@@ -170,8 +170,8 @@ static int mlx4_en_dcbnl_ieee_setpfc(struct net_device *dev,
 			pfc->mbc,
 			pfc->delay);
 
-	prof->rx_pause = !!pfc->pfc_en;
-	prof->tx_pause = !!pfc->pfc_en;
+	prof->rx_pause = !pfc->pfc_en;
+	prof->tx_pause = !pfc->pfc_en;
 	prof->rx_ppp = pfc->pfc_en;
 	prof->tx_ppp = pfc->pfc_en;