net/mlx5: Rename FDB_* tc related defines to FDB_TC_* defines

Rename it to prepare for next patch that will add a
different type of offload to the FDB.

Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>