When hotplug slot is under the host bridge,
DEVICE_ACPI_HANDLE(&bus->self->dev) fails since '&bus->self' was not set.
This patch fixes it.

This patch is based on kristen's latest patches.
I tested this patch on my Tiger4.
Signed-off-by: NMUNEDA Takahiro <muneda.takahiro@jp.fujitsu.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>