Instead of displaying the error on stderr, use error_report()
which also report to the monitor.

Reviewed-by: Fam Zheng <fam@euphon.net>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20210902070025.197072-3-philmd@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>