net/mlx5: Remove dependency of macsec flow steering on ethernet

Since macsec flow steering was moved to core, it should be independent
of all ethernet code and structures hence we remove all ethernet header
includes and redefine ethernet structs internally for macsec_fs usage
where needed.

Signed-off-by: Patrisious Haddad <phaddad@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>