multi-process: fix usage information From source code, the 'devid' of x-remote-object should be one of devices in remote QEMU process. Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com> Reviewed-by: Jagannathan Raman <jag.raman@oracle.com> Reviewed-by: Laurent Vivier <laurent@vivier.eu> Message-Id: <20210713004718.20381-1-dongli.zhang@oracle.com> Signed-off-by: Laurent Vivier <laurent@vivier.eu>