[NFC] polish colossalai/nn/parallel/data_parallel.py code style (#1570)

Co-authored-by: JThh <jiatong.han@u.nus.edu>

colossalai/nn/parallel/data_parallel.py

@@ -350,7 +350,7 @@ class ZeroDDP(ColoDDP):
             for tensor in chunk.get_tensors():
                 rec_p = torch.empty([0])
                 if record_flag:
-                    rec_p = tensor.cpu()  # move the whole tensor to CPU mem
+                    rec_p = tensor.cpu()    # move the whole tensor to CPU mem
                 assert tensor not in param_to_save_data
                 param_to_save_data[tensor] = rec_p
             # release the actual memory of the chunk
@@ -406,7 +406,7 @@ class ZeroDDP(ColoDDP):
         state_dict = state_dict.copy()
         if metadata is not None:
             # mypy isn't aware that "_metadata" exists in state_dict
-            state_dict._metadata = metadata  # type: ignore[attr-defined]
+            state_dict._metadata = metadata    # type: ignore[attr-defined]
 
         prefix = ''
         local_metadata = {} if metadata is None else metadata.get(prefix[:-1], {})