net/mlx5: Simplify fdb chain and prio eswitch defines

FDB_MAX_CHAIN and FDB_MAX_PRIO were defined differently depending
on if CONFIG_MLX5_ESWITCH is enabled to save space on allocations.

This is a minor space saving, and there is no real need for it.
Simplify things instead, and define them the same in both cases.

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>