ACPI: APEI: Remove a useless include

This file does not use rcu, so there is no point in including
<linux/rculist.h>.

So just remove it.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>