[Bug] Ensure lr scheduler uses limit_train_batches when working out max steps
Hi, thanks for the bugfix! Could you fix the style issues by running `python setup.py style --scope=nemo/ --fix` ? Oh theres also a style issue in tests so another pass of  `python setup.py style --scope=tests/ --fix`  @SeanNaren Thanks for the test fix, youll need to run style fixes as mentioned above to pass the tests. Thanks @titu1994! Should be fixed :)  Perfect, thanks ! Thanks @SeanNaren! Thank you guys :)
When `limit_train_batches` is different to the default, this is not included in the inferred calculation of max_steps. This leads to the incorrect schedule being used when `limit_train_batches` is used.

This PR adds `limit_train_batches` to the calculation to ensure the schedule is correct!