Fix whisper compile

[jiqing-feng]

This change could fix the whisper compile error.
Besides, we don't need cache here, this change also avoids the log warning [here].

To reproduce the error:

import torch
from transformers import pipeline
from datasets import load_dataset

pipe = pipeline("automatic-speech-recognition", model="openai/whisper-small")
pipe.model.forward = torch.compile(pipe.model.forward)
ds = load_dataset("hf-internal-testing/librispeech_asr_dummy", "clean", split="validation")
sample = ds[0]["audio"]
prediction = pipe(sample.copy(), batch_size=8)["text"]
print(prediction)

Traceback:

...
    if truth_fn(mod):
  File "/home/jiqing/transformers/src/transformers/cache_utils.py", line 405, in __len__
    return len(self.key_cache)
  File "/usr/local/lib/python3.10/dist-packages/torch/nn/modules/module.py", line 1931, in __getattr__
    raise AttributeError(
torch._dynamo.exc.InternalTorchDynamoError: AttributeError: 'DynamicCache' object has no attribute 'key_cache'