[Ascend] Fix missing accum_dtype param in fused_linear_jsd forward

[TecJesh]

Summary

Fix TypeError in Ascend backend's LigerFusedLinearJSDFunction.forward() caused by a missing accum_dtype parameter.
When running the fused_linear_jsd test on Ascend NPU, the following error occurs:
TypeError: LigerFusedLinearJSDFunction.forward() takes from 5 to 9 positional arguments but 10 were given
Add the missing accum_dtype: Optional[torch.dtype] = None parameter in three locations within backends/_ascend/ops/fused_linear_jsd.py

Testing Done

• Hardware Type: Atlas 800I A2
• run make test to ensure correctness
• run make checkstyle to ensure code style
• run make test-convergence to ensure convergence