There is no need to define QEMUMonitorProtocol as old-style class.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20170818142613.32394-8-ldoktor@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>