Fix typo in QEMU migration command name

The QMP code was running query-migration instead of query-migrate.
This doesn't work so well

* src/qemu/qemu_monitor_json.c: s/query-migration/query-migrate/

src/qemu/qemu_monitor_json.c

@@ -1108,7 +1108,7 @@ int qemuMonitorJSONGetMigrationStatus(qemuMonitorPtr mon,
                                       unsigned long long *total)
 {
     int ret;
-    virJSONValuePtr cmd = qemuMonitorJSONMakeCommand("query-migration",
+    virJSONValuePtr cmd = qemuMonitorJSONMakeCommand("query-migrate",
                                                      NULL);
     virJSONValuePtr reply = NULL;