fix: prevent fp8 mma dot from lowering to fp16 on sm120

[stmoonar]

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Description

When using triton dist write fp8 gemm kernel on RTX PRO5000(sm120), found that the gemm time in the intra profile is not better than fp16.
Then use ncu profile the gemm kernel, found it used fp16->fp32 mma instead of fp8_>fp32 mma:

Solution

Found the pr in triton upstream that solve this: triton-lang#7409

Fixed Result

Using ncu profile again: