sched/deadline: Add replenish_dl_new_period helper

Wrap repeated code in helper function replenish_dl_new_period, which set
the deadline and runtime of input dl_se based on pi_of(dl_se). Note that
setup_new_dl_entity originally set the deadline and runtime base on
dl_se, which should equals to pi_of(dl_se) for non-boosted task.

Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Link: https://lore.kernel.org/r/20220826100037.12146-1-shangxiaojing@huawei.com