[moe] fix: correct the cache size in the last chunk (#3679)

Co-authored-by: Abatom <abzhonghua@gmail.com>

python/sglang/srt/layers/moe/fused_moe_triton/fused_moe.py

@@ -1064,7 +1064,9 @@ def fused_experts_impl(
             # so the cache size and config are already set correctly and
             # do not need to be adjusted.
             intermediate_cache1 = intermediate_cache1[:tokens_in_chunk]
-            intermediate_cache2 = intermediate_cache2[:tokens_in_chunk]
+            intermediate_cache2 = intermediate_cache2[
+                : tokens_in_chunk * topk_ids.shape[1]
+            ]
             intermediate_cache3 = intermediate_cache3[:tokens_in_chunk]
             config = get_config_func(tokens_in_chunk)