fix grouped_topk tl.sort when numel=1 (#1101)

Co-authored-by: sangchengmeng <[email protected]>

Author: SangChengC

lightllm/common/fused_moe/grouped_topk.py

@@ -159,7 +159,10 @@ def grouped_topk_kernel(
         axis=1,
     )
 
-    sorted_group_value = tl.sort(group_value, descending=True)
+    if EXPERT_GROUP_NUM > 1:
+        sorted_group_value = tl.sort(group_value, descending=True)
+    else:
+        sorted_group_value = group_value
     group_topk_value = tl.sum(tl.where(offs_group == group_topk_num - 1, sorted_group_value, 0.0))
     mask_group_scores = tl.where(
         ((group_value >= group_topk_value)[:, None]) & ((offs_group_v < group_expert_num)[None, :]),