net/mlx5: Fix condition for termination table cleanup

When we destroy rules from slow path we need to avoid destroying
termination tables since termination tables are never created in slow
path. By doing so we avoid destroying the termination table created for the
slow path.

Fixes: d8a2034f

 ("net/mlx5: Don't use termination tables in slow path")
Signed-off-by: Eli Cohen <eli@mellanox.com>
Reviewed-by: Oz Shlomo <ozsh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>