nbd: Allow description when creating NBD blockdev

Allow blockdevs to match the feature already present in qemu-nbd -D.
Enhance iotest 223 to cover it.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20191114024635.11363-5-eblake@redhat.com>
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index d0e0af8..558fe06 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -2351,7 +2351,7 @@
             continue;
         }
 
-        qmp_nbd_server_add(info->value->device, false, NULL,
+        qmp_nbd_server_add(info->value->device, false, NULL, false, NULL,
                            true, writable, false, NULL, &local_err);
 
         if (local_err != NULL) {
@@ -2373,7 +2373,7 @@
     bool writable = qdict_get_try_bool(qdict, "writable", false);
     Error *local_err = NULL;
 
-    qmp_nbd_server_add(device, !!name, name, true, writable,
+    qmp_nbd_server_add(device, !!name, name, false, NULL, true, writable,
                        false, NULL, &local_err);
     hmp_handle_error(mon, local_err);
 }