hexagon: Flash Attention optimizations (dma, mpyacc, multi-row) and MatMul updates...

hexagon: Flash Attention optimizations (dma, mpyacc, multi-row) and MatMul updates (llama/20118)

* ggml-hexagon: enhance hvx_dot_f16_f16_aa_rx4 for improved performance by expanding vector handling and optimizing accumulation

# Conflicts:
#	ggml/src/ggml-hexagon/htp/flash-attn-ops.c

* ggml-hexagon: optimize hvx_dot_f16_f16_aa_rx4 and enhance hvx_vec_reduce_sum_f32x4 for improved performance and reduced complexity

* ggml-hexagon: add hvx_dot_f16_f16_aa_rx32 for enhanced vector processing in flash attention

# Conflicts:
#	ggml/src/ggml-hexagon/htp/flash-attn-ops.c

* optimize hvx_dot_f16_f16_aa_rx4 and hvx_dot_f16_f16_aa_rx32 by removing unused scale parameter and improving vector accumulation

# Conflicts:
#	ggml/src/ggml-hexagon/htp/flash-attn-ops.c

* ggml-hexagon: refactor hvx_dot_f16_f16_aa_rx4 for improved readability and return HVX_Vector for better integration

# Conflicts:
#	ggml/src/ggml-hexagon/htp/flash-attn-ops.c

* ggml-hexagon: initialize sums variable in hvx_dot_f16_f16_aa_rx32 for clarity

* ggml-hexagon: fix compiling error

* fix hvx_dot_f16_f16_aa_rx4 to handle leftover elements correctly using masking

* refactor hvx_dot_f16_f16_aa_rx4 to accept vector and leftover element counts as parameters for improved clarity and flexibility

* wip

* fa: instrumentation and dma reordering

* hex-fa: use block-size 64 to improve DMA pipelining

* hex-fa: optimize vec-dot for v79 and above

* hex-fa: use block size 64

* hex-fa: avoid scalar fp32->fp16 conversions

* hex-fa: simplify dot_f16 functions using optimized vec_mpyacc

* hex-fa: rewrite mad_f32_f16 using hvx_vec_mpyacc

* hex-mm: use mpyacc in matmul dot functions

---------

Co-authored-by: chraac <redacted>