Revert "virtio-balloon: Revert "virtio-balloon: Switch back to OOM handler for VIRTIO...

Revert "virtio-balloon: Revert "virtio-balloon: Switch back to OOM handler for VIRTIO_BALLOON_F_DEFLATE_ON_OOM""

This reverts commit 37681282be8e89ae8baf26753bf489837d74e08e which is
commit 835a6a649d0dd1b1f46759eb60fff2f63ed253a7 upstream.

Jiri and David agree that it is not needed in the 5.6.y tree, so revert
it.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: David Hildenbrand <david@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>