sched/fair: Make update_entity_lag() static

The function update_entity_lag() is only used inside the kernel/sched/fair.c file.
Make it static.
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230829030325.69128-1-jiahao.os@bytedance.com

kernel/sched/fair.c

@@ -699,7 +699,7 @@ u64 avg_vruntime(struct cfs_rq *cfs_rq)
  *
  * XXX could add max_slice to the augmented data to track this.
  */
-void update_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static void update_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
 	s64 lag, limit;