sb/intel/lynxpoint: Move IOBP API to its own compilation unit

Change-Id: Icb6114302cebe19bc3c1971929ea4fc085b454be
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41946
Reviewed-by: Michael Niewöhner
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Jonathan Kollasch <jakllsch@kollasch.net>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/southbridge/intel/lynxpoint/serialio.c

@@ -8,6 +8,7 @@
 #include <device/pci.h>
 #include <device/pci_ids.h>
 #include "chip.h"
+#include "iobp.h"
 #include "pch.h"
 #include "nvs.h"