util: save hostdev network device config before unbinding from host driver
    
    In order to properly restore the original state of an SRIOV VF when
    we're finished with it, we need to save the MAC address of the VF
    itself (not just the admin MAC address for the VF that is stored in
    the PF). But that can only be done when the VF is still bound to the
    host's netdev driver, and we have always done the saving of device
    config after the VF is already bound to vfio-pci. This patch prepares
    us for adding a save of the VF's MAC by calling the function that
    saves netconfig earlier in the device preparation, before we've
    unbound it from the host netdev driver.