replace rt_enter_critical with dfs_lock for list_fd

I found that if use mutex in `rt_kprintf`,
the `rt_enter_critical` will create a assert
error later. after chehcking,I found all
operation with fd_table has using
`dfs_lock/unlock` to protect. so I think
using `dfs_lock` is enough. thanks.

Signed-off-by: a1012112796 <1012112796@qq.com>

components/dfs/src/dfs.c

@@ -529,7 +529,7 @@ int list_fd(void)
     fd_table = dfs_fdtable_get();
     if (!fd_table) return -1;
 
-    rt_enter_critical();
+    dfs_lock();
 
     rt_kprintf("fd type    ref magic  path\n");
     rt_kprintf("-- ------  --- ----- ------\n");
@@ -562,7 +562,7 @@ int list_fd(void)
             }
         }
     }
-    rt_exit_critical();
+    dfs_unlock();
 
     return 0;
 }