K8: Fix indirect includes

Change-Id: I370285aa52776170a32b6dd36c0eef74eea9400c
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/20562
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/cpu/amd/model_fxx/init_cpus.c

@@ -11,7 +11,9 @@
  * GNU General Public License for more details.
  */
 
+#include <cpu/amd/mtrr.h>
 #include <cpu/x86/lapic.h>
+#include <cpu/x86/mtrr.h>
 #include <northbridge/amd/amdk8/amdk8.h>
 #include "cpu/amd/car/post_cache_as_ram.c"