[ROCm] Enable chunked prefill/paged attention in MLA on ROCm

[SageMoore]

This PR is largely just removing the guards in config.py to allow chunked prefill and paged attention in MLA. The LSE computation in the triton kernel doesn't work so we always fall back to flash attention in this case.

I ran lm_eval --model vllm --model_args pretrained=deepseek-ai/DeepSeek-Coder-V2-Lite-Instruct,trust_remote_code=True,enable_chunked_prefill=True --tasks gsm8k --num_fewshot 5 --batch_size auto and got

vllm (pretrained=deepseek-ai/DeepSeek-Coder-V2-Lite-Instruct,trust_remote_code=True,enable_chunked_prefill=True), gen_kwargs: (None), limit: None, num_fewshot: 5, batch_size: auto
|Tasks|Version|     Filter     |n-shot|  Metric   |   |Value |   |Stderr|
|-----|------:|----------------|-----:|-----------|---|-----:|---|-----:|
|gsm8k|      3|flexible-extract|     5|exact_match|↑  |0.7612|±  |0.0117|
|     |       |strict-match    |     5|exact_match|↑  |0.7437|±  |0.0120|

CC: @LucasWilkinson

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[vincent-4]

Thoughts?

[shajrawi]

Nice! Thank you - cc @mawong-amd

[houseroad]

The changes look good to me. The changes are only applied to hip, and straightforward.

[LucasWilkinson]

LGTM now, thanks!