The option is only a dummy since a long time. We've finally deprecated
it in QEMU v3.0, so it's time to remove it now.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <1549545296-18903-3-git-send-email-thuth@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>