fix: fix cache length

Author: niushengxiao

lightllm/server/httpserver/manager.py

@@ -704,7 +704,7 @@ async def _wait_to_token_package(
                     prompt_cache_len = metadata.pop("prompt_cache_len", 0)
                     cpu_prompt_cache_len = metadata.pop("cpu_prompt_cache_len", 0)
                     disk_prompt_cache_len = metadata.pop("disk_prompt_cache_len", 0)
-                    metadata["prompt_cache_len"] = prompt_cache_len
+                    metadata["prompt_cache_len"] = prompt_cache_len + cpu_prompt_cache_len + disk_prompt_cache_len
                     sub_req_id_to_mtp_accepted_token_num[sub_req_id] = metadata.get("mtp_accepted_token_num", 0)
 
                     if is_first_token: