fix chdir for ash's cd (#8824)

components/dfs/dfs_v2/src/dfs_posix.c

@@ -1180,6 +1180,7 @@ int chdir(const char *path)
         /* this is a not exist directory */
         dfs_unlock();
 
+        rt_set_errno(-ENOTDIR);
         return -1;
     }