net/mlx5: Remove all auxiliary devices at the unregister event

The call to mlx5_unregister_device() means that mlx5_core driver is
removed. In such scenario, we need to disregard all other flags like
attach/detach and forcibly remove all auxiliary devices.

Fixes: a5ae8fc9 ("net/mlx5e: Don't create devices during unload flow")
Tested-and-Reported-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>