ggml-hexagon: Implement true Q8_0 quantization on Hexagon NPU for more accurate mixed-precision matmul operations (#17977)

* feat: implement real Q8_0

* feat: adding cmake option for configuring FP32 quantize group size

* typo: set() shall be used

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Co-authored-by: ngdxzy <zhenyu_xu@uri.edu>

ggml/src/ggml-hexagon/htp/CMakeLists.txt

@@ -31,7 +31,8 @@ add_library(${HTP_LIB} SHARED
 )
 
 target_compile_definitions(${HTP_LIB} PRIVATE
-    $<IF:$<BOOL:${HEXAGON_HTP_DEBUG}>,HTP_DEBUG=1,NDEBUG=1>)
+    $<IF:$<BOOL:${HEXAGON_HTP_DEBUG}>,HTP_DEBUG=1,NDEBUG=1>
+    FP32_QUANTIZE_GROUP_SIZE=${GGML_HEXAGON_FP32_QUANTIZE_GROUP_SIZE})
 
 build_idl(htp_iface.idl ${HTP_LIB})