Qwen3 next -- fixed conv update split q/k/v in decode phase

[IzacharyI]

Motivation

fixed conv update split q/k/v in decode phase

Modifications

fixed conv update split q/k/v in decode phase

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.