PCI: fix pciehp_free_irq()

This patch fixes an obvious bug (loop was never entered) caused by
commit 820943b6


(pciehp: cleanup pcie_poll_cmd).

Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>