This allows to get rid of a call to qdev_get_machine().

Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20200106145645.4539-8-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>