Fix loading for newer m2m models
Newer version of m2m models have args parameter as None.

args are present in cfg['model']. Fixing input arguments to the function as well.




Thanks for the PR @harveenchadha !
Could you post the link for the new m2m models, I couldn't find anything new here https://github.com/pytorch/fairseq/tree/master/examples/m2m_100<|||||>Hey Suraj, from newer models I mean models trained with newer version of fairseq. I was trying to convert [Indic Trans](https://github.com/AI4Bharat/indicTrans) and ran into issues using this script.<|||||>I see, thanks! PR looks good, just one style check is failing, you could fix it by running `make style` and `make quality`.<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md) are likely to be ignored.<|||||>gently pinging @harveenchadha :) <|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md) are likely to be ignored.