IB/mlx5: Add sniffer support to steering

Add support to create sniffer rule. This rule receive all
incoming and outgoing packets from the port.
A user could create such rule by using IB_FLOW_ATTR_SNIFFER type.

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>