pciehp: evaluate _OSC/OSHP before controller init

Current pciehp evaluates _OSC/OSHP method after some controller
initialization is done. So if evaluating _OSC/OSHP is failed, we need
to cleanup already initialized data structures or hardware. This
clearly is not robust way. With this patch, _OSC/OSHP evaluation is
done first.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>