ACPI / dock: Walk list in reverse order during removal of devices

If there are indirect dependencies between devices in a dock
station's dependent devices list, they may be broken if the devices
are removed in the same order in which they have been added.

For this reason, make the code in handle_eject_request() walk the
list of dependent devices in reverse order.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>