PCI hotplug: pciehp: remove unnecessary wait after turning power off

The pciehp driver waits for 1000 msec after turning power off to make
sure the power has been completely removed. But this 1000 msec wait is
not needed if a slot doesn't implement power control because software
cannot control the power. Power will be automatically removed at adapter
removal time on such a slot

Tested-by: "Phil Endecott" <phil_pibbu_endecott@chezphil.org>
Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>