[release/2.12] [ROCm] Add initial support for gfx1250 (#188597)

[rraminen]

Summary

Validation theRock Run: https://github.com/ROCm/TheRock/actions/runs/29045360944

Cherry-pick of upstream pytorch/pytorch#188597 onto release/2.12 to add initial ROCm support for gfx1250 (CDNA5).

Co-authored-by: @glen-amd

What this PR enables

• Gates gfx1250-specific behavior on ROCm 7.14+ (the support floor), applied consistently across CUDABlas.cpp, ScaledBlas.cpp, CUDAHooks.cpp, and the test helpers.
• Adds gfx1250 to the hipBLASLt preferred/supported arch lists and the hipSparseLt support check (ROCm 7.14+).
• Extends the scaled GEMM / MX-format paths (block-wise Float8_e8m0fnu, mxfp8, mxfp4) to gfx1250.
• Sets the gfx1250 shared-memory limit to 320 KB (vs 160 KB on gfx950), matching on the suffix-stripped arch name.
• Adds CDNA2/CDNA3/CDNA5 "or later" arch helpers and updates FP8 / MX GEMM test gating in common_cuda.py.
• Builds Composable Kernel (CK) GEMM as a separate ck_gemm library with gfx1250 filtered out of HIP_ARCHITECTURES, so a multi-arch build that includes gfx1250 keeps CK GEMM for the other archs instead of failing to compile for gfx1250 (composable_kernel has no gfx1250 support yet). The filter is removed once CK supports gfx1250.
• Extends the gfx942 nontemporal vectorized-load path in MemoryAccess.cuh to gfx1250.
• Refactors duplicated arch-check logic in CUDABlas.cpp, ScaledBlas.cpp, and cuSPARSELtOps.cpp per review feedback.
• Writes the CublasHandlePool workspace archs in full (gfx942/gfx950/gfx1250).

Enabled via the main merge:

• Flash attention and memory-efficient attention on gfx1250 via AOTriton 0.12.1b (from [ROCm] Support USE_ASAN=1 build pytorch/pytorch#188242), which this branch merges in.

What is not enabled yet:

• CK SDPA on gfx1250: composable_kernel has no gfx1250 support; the CK SDPA target auto-filters to gfx942/gfx950.
• CK GEMM on gfx1250: filtered out (see above) until composable_kernel supports it.
• FP8 grouped GEMM on gfx1250: MSLK builds only gfx942/gfx950.
• int4 mm on gfx1250: the tinygemm MFMA kernel needs a WMMA port; the ops return a clear "not supported yet" error and the int4 unit tests skip gfx1250.

CI note:

• gfx1250 is not added to the ROCm 7.2 (rocm-n) docker image, whose HIP compiler cannot target gfx1250. gfx1250 CI belongs on the nightly ROCm image and is added in a follow-up.

Co-authored-by: @glen-amd

References

• Upstream PR: [ROCm] Add initial support for gfx1250 pytorch/pytorch#188597
• Related AOTriton bump: [ROCm] Support USE_ASAN=1 build pytorch/pytorch#188242

[rocm-repo-management-api]

Jenkins build for 6722f8ea68735ee20455fffae1907038ff0185f9 commit is in progress
Links: Pipeline Overview / Build artifacts

[jithunnair-amd]

LGTM, but please verify build and test changes via theRock CI to ensure we are not introducing breakages.