mlxsw: spectrum_acl: Don't migrate already migrated entry

Check if the entry is already in a chunk where we want it to be. In that
case, skip migration. This is preparation for "per parts" migration
where this situation may occur.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>