Remove unused row_idx in token_dispatcher (#3442)

### What this PR does / why we need it?
The `row_idx` parameter is no longer used since
PR[#2689](https://github.com/vllm-project/vllm-ascend/pull/2689), so
remove it across multiple files to remove unnecessary calculations and
parameter passing.

### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
accuracy test passed for Qwen3 235B and DeepSeek V3 671B after this PR.


- vLLM version: v0.11.0rc3
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0

---------

Signed-off-by: CaranLic <740821011@qq.com>

vllm_ascend/quantization/w4a8_dynamic.py

@@ -265,7 +265,7 @@ class AscendW4A8DynamicFusedMoEMethod:
             1] == global_num_experts, "Number of global experts mismatch"
 
         # NOTE: now npu_moe_gating_top_k can only support `group_count=256` pattern
-        topk_weights, topk_ids, row_idx = select_experts(
+        topk_weights, topk_ids = select_experts(
             hidden_states=x,
             router_logits=router_logits,
             top_k=top_k,
@@ -297,7 +297,6 @@ class AscendW4A8DynamicFusedMoEMethod:
             w2_scale_bias=layer.w2_scale_bias,
             topk_weights=topk_weights,
             topk_ids=topk_ids,
-            row_idx=row_idx,
             use_int4_w4a8=True,
             expert_map=expert_map,
             log2phy=log2phy,

vllm_ascend/quantization/w8a8_dynamic.py

@@ -205,7 +205,7 @@ class AscendW8A8DynamicFusedMoEMethod:
         assert router_logits.shape[
             1] == global_num_experts, "Number of global experts mismatch"
 
-        topk_weights, topk_ids, row_idx = select_experts(
+        topk_weights, topk_ids = select_experts(
             hidden_states=x,
             router_logits=router_logits,
             top_k=top_k,
@@ -232,7 +232,6 @@ class AscendW8A8DynamicFusedMoEMethod:
                 w2=layer.w2_weight,
                 topk_weights=topk_weights,
                 topk_ids=topk_ids,
-                row_idx=row_idx,
                 use_int8_w8a8=True,
                 w1_scale=layer.w13_weight_scale,
                 w2_scale=layer.w2_weight_scale,
@@ -252,7 +251,6 @@ class AscendW8A8DynamicFusedMoEMethod:
             w2_scale=layer.w2_weight_scale,
             topk_weights=topk_weights,
             topk_ids=topk_ids,
-            row_idx=row_idx,
             use_int8_w8a8=True,
             expert_map=expert_map,
             log2phy=log2phy,