net/mlx4_en: Change min MTU size to ETH_MIN_MTU

NIC driver minimal MTU size shall be set to ETH_MIN_MTU, as defined in
the RFC791 and in the network stack. Remove old mlx4_en only define for
it, which was set to wrong value.

Fixes: b80f71f5 ("ethernet/mellanox: use core min/max MTU checking")
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -3493,8 +3493,8 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
 		dev->gso_partial_features = NETIF_F_GSO_UDP_TUNNEL_CSUM;
 	}
 
-	/* MTU range: 46 - hw-specific max */
-	dev->min_mtu = MLX4_EN_MIN_MTU;
+	/* MTU range: 68 - hw-specific max */
+	dev->min_mtu = ETH_MIN_MTU;
 	dev->max_mtu = priv->max_mtu;
 
 	mdev->pndev[port] = dev;

drivers/net/ethernet/mellanox/mlx4/mlx4_en.h

@@ -161,7 +161,6 @@
 #define MLX4_SELFTEST_LB_MIN_MTU (MLX4_LOOPBACK_TEST_PAYLOAD + NET_IP_ALIGN + \
 				  ETH_HLEN + PREAMBLE_LEN)
 
-#define MLX4_EN_MIN_MTU		46
 /* VLAN_HLEN is added twice,to support skb vlan tagged with multiple
  * headers. (For example: ETH_P_8021Q and ETH_P_8021AD).
  */