add fake for MLA RoPE operator

[mqhc2020]

Motivation

For the function fused_qk_rope_cat_and_cache_mla, SGLang needs fake for it to pass torch compile.

Technical Details

This commit will need another SGLang commit merged simultaneously, because the API is changed.

Test Plan

Test Result

Submission Checklist

• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

[Copilot]

Pull request overview

This PR adds torch.compile support for the fused_qk_rope_cat_and_cache_mla function by introducing a fake tensor function that simulates tensor shapes and dtypes without actual computation. This is required for SGLang's torch.compile integration.

• Adds fused_qk_rope_cat_and_cache_mla_fake_tensor function to generate fake tensors for torch.compile
• Updates return type to always return 5 tensors (including q_nope_zeros_out) for consistency
• Adds type hints and improves type annotations for better code clarity

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[k50112113]

Looks good! Thanks for the addition, I think we are not going to let torch compile see inside this function in any cases, so this is a pretty decent change.