ggml : update `ggml_rope_multi` (#12665)
* update `rope_multi`:
1. add `ggml_rope_multi_inplace`;
1. use `GGML_MROPE_SECTIONS` instead of 4.
* Apply suggestions from code review
Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
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Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
