qapi: Convert migrate_cancel

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
diff --git a/hmp.c b/hmp.c
index 934e931..92bb08f 100644
--- a/hmp.c
+++ b/hmp.c
@@ -662,3 +662,8 @@
     qmp_blockdev_snapshot_sync(device, filename, !!format, format, &errp);
     hmp_handle_error(mon, &errp);
 }
+
+void hmp_migrate_cancel(Monitor *mon, const QDict *qdict)
+{
+    qmp_migrate_cancel(NULL);
+}