virtio-mmio: stop ioeventfd on legacy reset

If the queue PFN is set to zero on a virtio-mmio device, the device is reset.
In that case however the virtio_bus_stop_ioeventfd function was not
called; add it so that the behavior is similar to when status is set to 0.

Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/virtio/virtio-mmio.c

@@ -376,6 +376,7 @@ static void virtio_mmio_write(void *opaque, hwaddr offset, uint64_t value,
             return;
         }
         if (value == 0) {
+            virtio_mmio_stop_ioeventfd(proxy);
             virtio_reset(vdev);
         } else {
             virtio_queue_set_addr(vdev, vdev->queue_sel,