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>
1 file changed