virtio-md-pci: Support unplug requests for compatible devices

Let's support unplug requests for virtio-md-pci devices that provide
a unplug_request_check() callback.

We'll wire that up for virtio-mem-pci next.

Message-ID: <20230711153445.514112-6-david@redhat.com>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
2 files changed