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

Use <arch/acpi.h> when appropriate.

Change-Id: I05a28d2c15565c21407101e611ee1984c5411ff0
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31781
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>

src/mainboard/emulation/qemu-q35/acpi_tables.c

@@ -17,7 +17,6 @@
 #include <string.h>
 #include <arch/acpi.h>
 #include <arch/ioapic.h>
-#include <arch/acpigen.h>
 #include <arch/smp/mpspec.h>
 #include <device/device.h>
 #include <device/pci.h>