Fix input typo in Whisper export with beam search (#16439)
### Description
This PR fixes a typo with assigning the `repetition_penalty` input in
the Whisper export with beam search model. It is a follow-up to the
[export stabilization
PR](https://github.com/microsoft/onnxruntime/pull/16297).
### Motivation and Context
The `repetition_penalty` input should be set to `repetition_penalty`
instead of `input_features`.
