pciehp: do not wake up irq_thread for sysfs operation

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

This patch fix the same issue as commit cdda3bbfd0ca ("pciehp: use
completion to wait irq_thread 'pciehp_ist'"). But the previous patch
didn't fix the issue completely. This patch power off the slot directly
instead of waking up the irq_thread 'pciehp_ist'

This patch also check 'slot_being_removed_rescanned' before powering off
the slot to avoid the dead lock issue similar as commit 764cafd9875e
("pciehp: fix a race between pciehp and removing operations by sysfs")

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