net/mlx5: Add sniffer namespaces

Add sniffer TX and RX namespaces to receive ingoing and outgoing
traffic.

Each outgoing/incoming packet is duplicated and steered to the sniffer
TX/RX namespace in addition to the regular flow.

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>