[gfx1250][FlyDSL] Optimize a8w8 ptpc gemm kernel

[aoli26]

Motivation

Update gfx1250 FlyDSL a8w8 bpreshuffle optimized kernel and tuned configs.

Technical Details

Update new optimized FlyDSL gfx1250 gemm a8w8 ptpc kernel and refresh a8w8_bpreshuffle_tuned_gemm.csv.

Test Plan

ENABLE_CK=0 python3 op_tests/test_gemm_a8w8.py --no-legacy

Test Result

All 48 flydsl-tuned shapes pass. Key gains (no regressions): (N=7168, K=16384) M=16: ~30us → ~10us (~3×); (N=2112, K=7168) M=16: ~7.5us → ~4.8us (~36%); remaining shapes improved or unchanged.

Submission Checklist

• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

[github-actions]

🏷️ CI Guide

Runs automatically on every PR:

• ✅ Pre-checks (submodule verification, code formatting)
• ✅ Aiter op tests (gfx942 + gfx950)
• ✅ Triton tests on MI35X (only when aiter/ops/triton/** or related paths are changed)

Extended tests (opt-in via labels):

Label	Tests
ci:triton-300x	Run an additional Triton test job on MI300X in PRs; main branch always runs both MI35X and MI300X
ci:sglang	SGLang integration tests: DeepSeek-R1-MXFP4 accuracy, Qwen 3.5 accuracy
ci:atom	ATOM benchmark: DeepSeek-R1-0528, GPT-OSS-120B
ci:atom_full	ATOM accuracy suite for PR and main models from ATOM models_accuracy.json
ci:vllm	vLLM benchmark: GPT-OSS-120B, DeepSeek-R1-0528, Kimi-K2.5
ci:all	All standard extended tests (excludes ci:atom_full)

Only add ci:atom_full for FlyDSL or Triton upgrades.
Add labels via the sidebar or gh pr edit 3969 --add-label <label>