net/mlx5: Lag, refactor disable flow

When a net device is removed (can happen if the PCI function is unbound
from the system) it's not enough to destroy the hardware lag. The system
should recreate the original devices that were present before the lag.
As the same flow is done when a net device is removed from the bond
refactor and reuse the code.

Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>