Getting error AttributeError: 'BertOnlyMLMHead' object has no attribute 'bias' when giving TF path
# 🐛 Bug

## Information

Model I am using BERT:

Language I am using the model on English:

The problem arises when using:
the official example scripts: 





The tasks I am working on is:
my own task or dataset: (give details below)

## To reproduce

Steps to reproduce the behavior:
I have this line in config class:

`    self.model_type = "bert"`

the config.model_name_or_path is the path where the checkpint file, index, meta config and vocab files are located
This is the problem with my code:
```
MODEL_CLASSES = {
  "bert": (BertConfig, BertForMaskedLM, BertTokenizer),
}
 config_class, model_class, tokenizer_class = MODEL_CLASSES[config.model_type]
  tokenizer = tokenizer_class.from_pretrained(config.model_name_or_path, cache_dir=None)
  gradients = []
  model_config = config_class.from_pretrained(config.model_name_or_path, cache_dir=None)

  model = model_class.from_pretrained(
    config.model_name_or_path,
    from_tf=True,
    config=model_config,
    cache_dir=None,
  )
```
I am getting this error :
```
  File "\transformers\src\transformers\modeling_utils.py", line 481, in from_pretrained
    model = cls.load_tf_weights(model, config, resolved_archive_file[:-6])  # Remove the '.index'
  File "\transformers\src\transformers\modeling_bert.py", line 105, in load_tf_weights_in_bert
    pointer = getattr(pointer, "bias")
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\site-packages\torch\nn\modules\module.py", line 576, in __getattr__
    type(self).__name__, name))
AttributeError: 'BertOnlyMLMHead' object has no attribute 'bias'

Process finished with exit code 1

I tried to convert the TF model to Pytorch model, but I am always getting the same error (from each script on different attribute).

```

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## Expected behavior
I expect the "from_pretrained" to load the TF model
<!-- A clear and concise description of what you would expect to happen. -->

## Environment info
<!-- You can run the command `transformers-cli env` and copy-and-paste its output below.
     Don't forget to fill out the missing fields in that output! -->
     
- `transformers` version:
- Platform: windows
- Python version: 3.7
- PyTorch version no
- Tensorflow version 2.1.0:
- Using GPU in script: no
- Using distributed or parallel set-up in script: no

To load TF models you should use the TF class `TFBertForMaskedLM` and not `BertForMaskedLM` which is the PyTorch class.<|||||>Thanks for the response
I found that  BertForPreTraining also allows to loads when the TF model<|||||>This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.
