Upload: fix default status of fileList (#6571)

packages/upload/src/index.vue

@@ -127,7 +127,7 @@ export default {
       handler(fileList) {
         this.uploadFiles = fileList.map(item => {
           item.uid = item.uid || (Date.now() + this.tempIndex++);
-          item.status = 'success';
+          item.status = item.status || 'success';
           return item;
         });
       }