net/mlx4_en: Fix the return value of mlx4_en_dcbnl_set_state()

mlx4_en_dcbnl_set_state() returns u8, the return value from
mlx4_en_setup_tc() could be negative in case of failure, so fix that.

Fixes: af7d5185 ("net/mlx4_en: Add DCB PFC support through CEE netlink commands")
Signed-off-by: NKamal Heib <kamalh@mellanox.com>
Signed-off-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

@@ -239,7 +239,10 @@ static u8 mlx4_en_dcbnl_set_state(struct net_device *dev, u8 state)
 		priv->flags &= ~MLX4_EN_FLAG_DCB_ENABLED;
 	}
 
-	return mlx4_en_setup_tc(dev, num_tcs);
+	if (mlx4_en_setup_tc(dev, num_tcs))
+		return 1;
+
+	return 0;
 }
 
 /* On success returns a non-zero 802.1p user priority bitmap