mainboard/google: Fix indirect includes

Change-Id: Ie79702efab519b16cff45ccad61b95e7d8c2fbac
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34854
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/cannonlake/memmap.c

@@ -17,6 +17,7 @@
 #include <arch/ebda.h>
 #include <cbmem.h>
 #include <console/console.h>
+#include <cpu/x86/smm.h>
 #include <device/device.h>
 #include <device/pci.h>
 #include <fsp/util.h>