mlx4: TCP/UDP packets have L4 hash

mlx4: TCP/UDP packets have L4 hash

Mellanox driver has the knowledge if rxhash is a L4 hash,
if it receives a non fragmented TCP or UDP frame and
NETIF_F_RXCSUM is enabled on netdev.

ip_summed value is CHECKSUM_UNNECESSARY in this case.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Amir Vadai <amirv@mellanox.com>
Cc: Ido Shamay <idos@mellanox.com>
Acked-by: Ido Shamay <idos@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>