[Refactor] Remove useless syncwarp (#30510)

Signed-off-by: yewentao256 <zhyanwentao@126.com>

csrc/moe/grouped_topk_kernels.cu

@@ -481,8 +481,6 @@ __device__ void topk_with_k2(T* output, T const* input, T const* bias,
       largest = value;
     }
   }
-
-  __syncwarp();  // Ensure all threads have valid data before reduction
   // Get the top2 warpwise
   T max1 = cg::reduce(tile, largest, cg::greater<T>());
 
@@ -589,7 +587,6 @@ __global__ void group_idx_and_topk_idx_kernel(
     int pre_count_equal_to_top_value = 0;
     // Use loop to find the largset top_group
     while (count_equal_to_top_value < target_num_min) {
-      __syncwarp();  // Ensure all threads have valid data before reduction
       topk_group_value = cg::reduce(tile, value, cg::greater<T>());
       if (value == topk_group_value) {
         value = neg_inf<T>();
@@ -644,10 +641,8 @@ __global__ void group_idx_and_topk_idx_kernel(
       }
     }
     queue.done();
-    __syncwarp();
     // Get the topk_idx
     queue.dumpIdx(s_topk_idx);
-    __syncwarp();
   }
 
   // Load the valid score value