virtio-balloon: fix memory leak while attach virtio-balloon device

ivq/dvq/svq/free_page_vq is forgot to cleanup in
virtio_balloon_device_unrealize, the memory leak stack is as follow:

Direct leak of 14336 byte(s) in 2 object(s) allocated from:
    #0 0x7f99fd9d8560 in calloc (/usr/lib64/libasan.so.3+0xc7560)
    #1 0x7f99fcb20015 in g_malloc0 (/usr/lib64/libglib-2.0.so.0+0x50015)
    #2 0x557d90638437 in virtio_add_queue hw/virtio/virtio.c:2327
    #3 0x557d9064401d in virtio_balloon_device_realize hw/virtio/virtio-balloon.c:793
    #4 0x557d906356f7 in virtio_device_realize hw/virtio/virtio.c:3504
    #5 0x557d9073f081 in device_set_realized hw/core/qdev.c:876
    #6 0x557d908b1f4d in property_set_bool qom/object.c:2080
    #7 0x557d908b655e in object_property_set_qobject qom/qom-qobject.c:26

Reported-by: Euler Robot <[email protected]>
Signed-off-by: Pan Nengyuan <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Reviewed-by: Michael S. Tsirkin <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>

Author: panny060

hw/virtio/virtio-balloon.c

@@ -831,6 +831,13 @@ static void virtio_balloon_device_unrealize(DeviceState *dev, Error **errp)
     }
     balloon_stats_destroy_timer(s);
     qemu_remove_balloon_handler(s);
+
+    virtio_delete_queue(s->ivq);
+    virtio_delete_queue(s->dvq);
+    virtio_delete_queue(s->svq);
+    if (s->free_page_vq) {
+        virtio_delete_queue(s->free_page_vq);
+    }
     virtio_cleanup(vdev);
 }