monitor: Convert do_set_link() to QObject, QError

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
diff --git a/qemu-monitor.hx b/qemu-monitor.hx
index 7b7dcf5..62fa346 100644
--- a/qemu-monitor.hx
+++ b/qemu-monitor.hx
@@ -989,7 +989,8 @@
         .args_type  = "name:s,up:b",
         .params     = "name on|off",
         .help       = "change the link status of a network adapter",
-        .mhandler.cmd = do_set_link,
+        .user_print = monitor_user_noop,
+        .mhandler.cmd_new = do_set_link,
     },
 
 STEXI