[Fix] Fix bug which breaks `cal_train_time` in `analyze_logs.py`. (#662)

* fix bug mmclassification issues 661

https://github.com/open-mmlab/mmclassification/issues/661

* fix lint

Co-authored-by: Zhicheng Chen <chen1319276472@foxmail.com>

tools/analysis_tools/analyze_logs.py

@@ -193,7 +193,7 @@ def parse_args():
     add_time_parser(subparsers)
     args = parser.parse_args()
 
-    if args.window_size != '':
+    if hasattr(args, 'window_size') and args.window_size != '':
         assert re.match(r'\d+\*\d+', args.window_size), \
             "'window-size' must be in format 'W*H'."
     return args