StoppingCriteria "scores" is always None
### System Info

I've written a custom StoppingCriteria subclass and I'm trying to utilize the `scores` in my decision logic, but I'm finding that `scores` is always `None`. Is that intentional?

### Who can help?

@patrickvonplaten, @Narsil, @gante

### Information

- [ ] The official example scripts
- [X] My own modified scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [X] My own task or dataset (give details below)

### Reproduction

```
class TopPredictionOutsideTargetSetStoppingCriteria(StoppingCriteria):
    def __init__(self, priority_tokens_ids: list):
        self.priority_token_ids = priority_tokens_ids

    def __call__(self, input_ids: torch.LongTensor, scores: torch.FloatTensor, **kwargs) -> bool:
        print(f"TopPred SCORES? {scores}, input_ids: {input_ids}")      # <--- "scores" is None but "input_ids" is correct
        top = torch.topk(scores, 1, dim=1).indices[0]
        if not top in self.priority_token_ids:
            return True
        return False
```

### Expected behavior

Since the function indicates `scores` as an input, I'd expect it to be a non-null value.
Hey @jbmaxwell, 

Sadly we don't have the time to dive into problems related to customized code. For this could you maybe try to use the forum instead? 

https://discuss.huggingface.co/

Looking at this line: https://github.com/huggingface/transformers/blob/ac98a88fbc6377f93e8b7fbd244b0c3331bb82a0/src/transformers/generation_utils.py#L1738 `scores` should not be `None` though.<|||||>Thanks for the reply. I understand about custom code. I just wanted to report that `scores` is `None`, and to confirm that this _shouldn't_ be the case.  I'll see if I can figure out how that's happening. <|||||>> Thanks for the reply. I understand about custom code. I just wanted to report that `scores` is `None`, and to confirm that this _shouldn't_ be the case. I'll see if I can figure out how that's happening.

hi,i have the same issue,how did you solve this problem？