ACPI / APEI: Remove arch_apei_flush_tlb_one()

Nothing calls arch_apei_flush_tlb_one() anymore, instead relying on
__set_pte_vaddr() to do the invalidation when called from clear_fixmap()
Remove arch_apei_flush_tlb_one().

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: All applicable <stable@vger.kernel.org>