fix grouped_topk tl.sort when numel=1

Author: sangchengmeng

lightllm/common/fused_moe/grouped_topk.py

@@ -159,8 +159,9 @@ def grouped_topk_kernel(
         axis=1,
     )
 
-    sorted_group_value = tl.sort(group_value, descending=True)
-    group_topk_value = tl.sum(tl.where(offs_group == group_topk_num - 1, sorted_group_value, 0.0))
+    if EXPERT_GROUP_NUM > 1:
+        group_value = tl.sort(group_value, descending=True)
+    group_topk_value = tl.sum(tl.where(offs_group == group_topk_num - 1, group_value, 0.0))
     mask_group_scores = tl.where(
         ((group_value >= group_topk_value)[:, None]) & ((offs_group_v < group_expert_num)[None, :]),
         group_scores,