pcie: Release references of virtual functions

pcie: Release references of virtual functions

pci_new() automatically retains a reference to a virtual function when
registering it so we need to release the reference when unregistering.

Fixes: 7c0fa8dff8 ("pcie: Add support for Single Root I/O Virtualization (SR/IOV)")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20230411090408.48366-1-akihiko.odaki@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>