Fixed a wrong parament name in printf

[Hustrookies]

1. 这个PR修复的是什么问题？ 根据前后文以及printf的信息，这里的printf("file_len is %d, remain_len = %d\r\n", file_len, read_len);应该改为printf("file_len is %d, remain_len = %d\r\n", file_len, remain_len);

2. 这个PR不修复具体会带来什么后果？ 错误的输出，且read_len未初始化，可能导致不确定行为

3. PR修复方案的依据是什么？ 前后文信息以及printf的输出提示信息

4. 在什么环境下测试或者验证过？ all

[tencent-adm]

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