pad_max_tiles (#5271)

Summary:
Land after: https://github.com/pytorch/torchtune/pull/1541

Propagate changes for `pad_max_tile` in ExecuTorch.

Pull Request resolved: https://github.com/pytorch/executorch/pull/5271

Test Plan:
```
python -m unittest examples/models/flamingo/preprocess/test_preprocess.py
```

Reviewed By: tarun292

Differential Revision: D62664973

Pulled By: lucylq

fbshipit-source-id: eb1523d741220a65c6e6dc4ab5342f2bbe5dc807