mlxsw: spectrum: lag resources- use resources data instead of consts

Use max lag and max ports in lag resources as the result of resource query
instead of using const to save them.

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