Update progress.py (#2268)

Fixes a minor bug introduced in #2213

Author: pwl

pytorch_lightning/callbacks/progress.py

@@ -97,8 +97,7 @@ def total_val_batches(self) -> int:
             total_val_batches = len(trainer.val_dataloaders)
         elif not self.trainer.disable_validation:
             is_val_epoch = trainer.current_epoch % trainer.check_val_every_n_epoch == 0
-            total_val_batches = trainer.num_val_batches if is_val_epoch else 0
-            total_val_batches = sum(total_val_batches)
+            total_val_batches = sum(trainer.num_val_batches) if is_val_epoch else 0
         return total_val_batches
 
     @property