Qwen3 next -- fixed sigmoid and mul broadcast issue

[IzacharyI]

Motivation

fixed sigmoid and mul broadcast issue

Modifications

• Remove autotune to fix repeated triggering issue across different sequence lengths
• Use fixed config BLOCK_N=32, BLOCK_H=1024
• Use in-place operation to avoid tensor allocation overhea

Accuracy Tests

Benchmarking and Profiling

Checklist

• Format your code according to the Format code with pre-commit.
• Add unit tests according to the Run and add unit tests.
• Update documentation according to Write documentations.
• Provide accuracy and speed benchmark results according to Test the accuracy and Benchmark the speed.
• Follow the SGLang code style guidance.
• Work with maintainers to merge your PR. See the PR Merge Process