fix at_client, avoid creating the same client repeatedly and prevent working exceptions and memory leaks.

- AT Socket feature supports multi-client connections;
- Fix `send data error, current socket (0) state (0) is error` issue when the socket is closed;
- Improve dirty data processing when AT device hard reset;
- Improve `at_obj_set_urc_table()` fucntion, Support for setting multiple URC tables;
- Improve RAW data print format;

Signed-off-by: chenyong <1521761801@qq.com>

correct a spelling mistake

修复LOG_X修改引起的编译错误