mlx4_en: UDP RSS support

Adding capability for RSS for UDP traffic, hashing is done based on
IP addresses and UDP port number.
The support depends on HW/FW capabilities.

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>