ggml : AVX512 gemm for Q4_0_8_8 (ggml-org#9532)

* AVX512 version of ggml_gemm_q4_0_8x8_q8_0

* Remove zero vector parameter passing

* Rename functions and rearrange order of macros

* Edit commments

* style : minor adjustments

* Update x to start from 0

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Co-authored-by: Georgi Gerganov <[email protected]>

Author: 2 people