Since PCI core and ACPI core already handles PCI PME wake and GPE wake
when the device has wakeup capability, use device_init_wakeup() to let
them do the wakeup setting work.

Also add a shutdown callback which uses pci_prepare_to_sleep() to let
PCI and ACPI set OOB wakeup for S5.

Cc: Jian Hui Lee <jianhui.lee@canonical.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>