[hotfix] fix initialize bug with zero (#442)

colossalai/amp/apex_amp/__init__.py

@@ -3,15 +3,13 @@ import torch.nn as nn
 from torch.optim import Optimizer
 
 
-def convert_to_apex_amp(model: nn.Module,
-                        optimizer: Optimizer,
-                        amp_config):
+def convert_to_apex_amp(model: nn.Module, optimizer: Optimizer, amp_config):
     """A helper function to wrap training components with Apex AMP modules
 
     :param model: your model object
     :type model: :class:`torch.nn.Module`
     :param optimizer: your optimizer object
-    :type optimizer: :class:`torch.optim.Optimzer`
+    :type optimizer: :class:`torch.optim.Optimizer`
     :param amp_config: configuration for nvidia apex
     :type amp_config: :class:`colossalai.context.Config` or dict