hmp: fix MemdevList memory leak

the memdev_list in hmp_info_memdev() is never freed.
so we use existent method qapi_free_MemdevList() to free it.
and also we can use qapi_free_MemdevList() to replace list loops
to clean up the memdev list in error path.
Signed-off-by: NChen Fan <chen.fan.fnst@cn.fujitsu.com>
Reviewed-by: NPeter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: NHu Tao <hutao@cn.fujitsu.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

hmp.c

@@ -1715,4 +1715,6 @@ void hmp_info_memdev(Monitor *mon, const QDict *qdict)
     }
 
     monitor_printf(mon, "\n");
+
+    qapi_free_MemdevList(memdev_list);
 }

numa.c

@@ -379,7 +379,7 @@ error:
 MemdevList *qmp_query_memdev(Error **errp)
 {
     Object *obj;
-    MemdevList *list = NULL, *m;
+    MemdevList *list = NULL;
 
     obj = object_resolve_path("/objects", NULL);
     if (obj == NULL) {
@@ -393,11 +393,6 @@ MemdevList *qmp_query_memdev(Error **errp)
     return list;
 
 error:
-    while (list) {
-        m = list;
-        list = list->next;
-        g_free(m->value);
-        g_free(m);
-    }
+    qapi_free_MemdevList(list);
     return NULL;
 }