fix(FA): QKV not being casted to target_dtype for FA with dpo lora
Author: NanoCode012
Pull request: yes

# What does this PR do?

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In DPO LORA, the QKV states aren't being casted to `target_dtype` raising `RuntimeError: FlashAttention only support fp16 and bf16 data type`.

This issue was created from the refactor in https://github.com/huggingface/transformers/pull/35342

The prior code checks if `query.dtype == torch.float32` and always casting it to fp16.
The current code checks if `query.dtype == torch.float32`, followed by `fa_peft_integration_check` check `if value.dtype == torch.float32` before casting to `target_dtype`.

From my debugging, 
```
TARGET DTYPE torch.bfloat16                                                                                                               
QUERY DTYPE torch.float32                                                                                                                 
KEY DTYPE torch.float32                                                                                                                   
VALUE DTYPE torch.bfloat16 
```

Since `value.dtype` is `bf16`, the cast does not occur. This PR fixes the check to use the same `query.dtype` check.

## How has this been tested?

I ran Axolotl CI, found the related commit to cause the error, tracked down this issue, and verified the fix solves it.

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