alinux: sched: Fix p->cpu build error on aarch64

to #27372989

CONFIG_THREAD_INFO_IN_TASK is not set for aarch64, task_struct has no
cpu member. We should use the helper functiton task_cpu instead.

Fixes: 9e7b35d6 ("alinux: sched: Introduce per-cgroup iowait accounting")
Signed-off-by: NYihao Wu <wuyihao@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

kernel/sched/fair.c

@@ -10042,7 +10042,7 @@ static void update_nr_iowait_fair(struct task_struct *p, long inc)
 	if (!schedstat_enabled())
 		return;
 
-	clock = __rq_clock_broken(cpu_rq(p->cpu));
+	clock = __rq_clock_broken(cpu_rq(task_cpu(p)));
 
 	for_each_sched_entity(se) {
 		/*