Use real-valued instead of complex tensors in Wan2.1 RoPE (#11649)
* use real instead of complex tensors in Wan2.1 RoPE
* remove the redundant type conversion
* unpack rotary_emb
* register rotary embedding frequencies as non-persistent buffers
* Apply style fixes
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Co-authored-by: Aryan <aryan@huggingface.co>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>