Clean up wrapper in flashinfer backend (#2638)

python/sglang/srt/managers/schedule_batch.py

@@ -843,8 +843,8 @@ class ScheduleBatch:
         # TODO (lianmin): Revisit this. It should be seq_len - 1
         self.extend_logprob_start_lens.extend([0] * running_bs)
 
-    def check_decode_mem(self):
-        bs = len(self.reqs)
+    def check_decode_mem(self, buf_multiplier=1):
+        bs = len(self.reqs) * buf_multiplier
         if self.token_to_kv_pool.available_size() >= bs:
             return True