Benchmark: Fix Bug - fix error message of communication-computation-overlap (#204)

**Description**
fix bug in error message of communication-computation-overlap.

**Major Revision**
- remove non existing variable

superbench/benchmarks/micro_benchmarks/computation_communication_overlap.py

@@ -264,11 +264,7 @@ def _postprocess(self):
             torch.distributed.destroy_process_group()
         except BaseException as e:
             self._result.set_return_code(ReturnCode.DISTRIBUTED_SETTING_DESTROY_FAILURE)
-            logger.error(
-                'Post process failed - benchmark: {}, mode: {}, message: {}.'.format(
-                    self._name, self._args.mode, str(e)
-                )
-            )
+            logger.error('Post process failed - benchmark: {}, message: {}.'.format(self._name, str(e)))
             return False
 
         return True