mmq.cu: tune mmq/rocblas switching for RDNA (#18537)
* Patch perf regression for mmq kernels in ROCm
recover performance regression for https://github.com/ggml-org/llama.cpp/issues/17917
* add n_experts branch like the cdna path
* mmq.cu: tune mmq/wmma switching for RDNA
* mmq.cu: move amd wmma mmq/wmma switching behind IS_RDNA3
* Update ggml/src/ggml-cuda/mmq.cu
Co-authored-by: Johannes Gäßler <johannesg@5d6.de>
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Co-authored-by: Jiacheng (Jason) Chen <76919340+jiachengjason@users.noreply.github.com>
Co-authored-by: jiachengjason <jasonchen.jiacheng@gmail.com>
Co-authored-by: Johannes Gäßler <johannesg@5d6.de>
