net/mlx4: Implement vxlan ndo calls

Add implementation for the add/del vxlan port ndo calls, using the
CONFIG_DEV firmware command.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/ethernet/mellanox/mlx4/en_netdev.c
Simple merge

diff --cc drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
Simple merge

diff --cc drivers/net/ethernet/mellanox/mlx4/port.c
Simple merge

diff --cc include/linux/mlx4/device.h
Simple merge