net/mlx5: Fix mlx5_ifc_query_lag_out_bits

Remove the "reserved_at_40" field to match the device specification.

Fixes: 84df61eb ("net/mlx5: Add HW interfaces used by LAG")
Signed-off-by: Mark Zhang <markz@mellanox.com>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>