修正宏定义的格式问题

user/apps/shell/shell.c

@@ -9,7 +9,7 @@
 #include "cmd.h"
 
 #define pause_cpu() asm volatile("pause\n\t");
-#define mem_history 1024
+#define MEM_HISTORY 1024
 /**
  * @brief 循环读取每一行
  *
@@ -22,7 +22,7 @@ int shell_readline(int fd, char *buf);
 void print_ascii_logo();
 extern char *shell_current_path;
 //保存的历史命令
-char history_commands[mem_history][INPUT_BUFFER_SIZE];
+char history_commands[MEM_HISTORY][INPUT_BUFFER_SIZE];
 int count_history;
 //现在对应的命令
 int pointer;