virtio: balloon: let host know of updated balloon size before module removal

When the balloon module is removed, we deflate the balloon, reclaiming
all the pages that were given to the host.  However, we don't update the
config values for the new balloon size, resulting in the host showing
outdated balloon values.

The size update is done after each leak and fill operation, only the
module removal case was left out.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index c2d05a8..8807fe5 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -390,6 +390,7 @@
 	/* There might be pages left in the balloon: free them. */
 	while (vb->num_pages)
 		leak_balloon(vb, vb->num_pages);
+	update_balloon_size(vb);
 
 	/* Now we reset the device so we can clean up the queues. */
 	vdev->config->reset(vdev);