IB/mlx5: Add support of more IPv6 fields to flow steering

Add support to receive Traffic Class, specific IPv6 protocol
or IPv6 flow label.

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>