pci: do not respond config requests after PCI device eject

pci: do not respond config requests after PCI device eject

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2224964
In migration with VF failover, Windows guest and ACPI hot
unplug we do not need to satisfy config requests, otherwise
the guest immediately detects the device and brings up its
driver. Many network VF's are stuck on the guest PCI bus after
the migration.

Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
Message-Id: <20230728084049.191454-1-yuri.benditovich@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 348e354417b64c484877354ee7cc66f29fa6c7df)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>