Use display device qdev id and head number instead of console index to
specify the QemuConsole.  This makes things consistent with input
devices (for input routing) and vnc server configuration, which both use
display and head too.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>