fix storage account nextLinkName (#11906)

Author: allenlsy-microsoft

specification/storage/resource-manager/Microsoft.Storage/preview/2020-08-01-preview/storage.json

@@ -452,7 +452,7 @@
           }
         },
         "x-ms-pageable": {
-          "nextLinkName": null
+          "nextLinkName": "nextLink"
         }
       }
     },