If a mod_file is out of kernel/sched, it cannot find relative include path

[dtcccc]

e.g., a file is at kernel/xxx/yyy.c

#include "zzz.h" -> this will include kernel/xxx/zzz.h

however, after init, this file will be at kernel/sched/mod/yyy.c

#include "../zzz.h" -> this will try to look for kernel/sched/zzz.h, but it not exists!