src: Drop unused 'include <arch/ioapic.h>'

Change-Id: I1341f90230f318ac81a4aea24872ff272adad1eb
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31856
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/slippy/acpi_tables.c

@@ -16,7 +16,6 @@
 #include <types.h>
 #include <string.h>
 #include <arch/acpi.h>
-#include <arch/ioapic.h>
 #include <arch/smp/mpspec.h>
 #include <device/device.h>
 #include <device/pci.h>