sched/fair: Make sync_entity_load_avg() and remove_entity_load_avg() static

sched/fair: Make sync_entity_load_avg() and remove_entity_load_avg() static

Fix these sparse warnigs:

  kernel/sched/fair.c:3570:6: warning: symbol 'sync_entity_load_avg' was not declared. Should it be static?
  kernel/sched/fair.c:3583:6: warning: symbol 'remove_entity_load_avg' was not declared. Should it be static?

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190320133839.21392-1-yuehaibing@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>