Fix nan issue for certain shape

[hebiao064]

I found that for certain shape such as (32, 128) * (128, 1024), if we replace aten::mm with matmul_persistent, the output would consist NaN hence generate gibberish output from LLMs.

I tried to fixed in by removing the dual pipeline logic(?) and it should work.

I've also tested with more shapes combination here: https://github.com/sgl-project/sglang/pull/11368/files#diff-fc88db1a639b98e0e4cceb66f72842a1612290664ba6753ad6f54d8276e0cd6aR88-R131

[Jah-yee]

Good day,

Thank you for digging into this tricky NaN issue! The root cause analysis with the shape combinations is very helpful.

I particularly appreciate the connection to the sglang PR - that's exactly the kind of cross-project collaboration that helps move the ecosystem forward.

Hope to see this merged soon!

Thank you for your work on this project...

Warmly, RoomWithOutRoof