This reverts commit 433efd22.

When we remove an SR-IOV device, we have this call chain:

    driver .remove() method
        pci_disable_sriov()
            sriov_disable()
                virtfn_remove()
                    pci_get_domain_bus_and_slot()

sriov_disable() is only called for PFs, not for VFs.  When it's called
for a PF, it loops through all the VFs and calls virtfn_remove() for
each.  But we stop and remove VFs before PFs, so by the time we get
to virtfn_remove(), the VFs have already been stopped and deleted
from the device list.  Now pci_get_domain_bus_and_slot(), which uses
bus_find_device() and relies on that device list, doesn't find the
VFs, so the VF references aren't released correctly.
Reported-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>