Revert "pciehp: use completion to wait irq_thread 'pciehp_ist'"

hulk inclusion
category: bugfix
bugzilla: NA
CVE: NA
-------------------

This reverts commit cdda3bbfd0cab7dea3cfb37e9a8648f945c0241d.

If 'slot_being_removed_rescanned' is set, when we power off the slot
through sysfs, the irq_thread 'pciehp_ist' will be woken up. But it will
return immediately and schedule this thread 3 seconds later. However,
sysfs write should wait until the actual operation is finished. We will
power off the slot in 'power_write_file' instread of waking up a
irq_thread. So this patch has no use. Let's revert it. A following patch
will fix the issue.

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: Yao Hongbo <yaohongbo@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>