northbridge/intel: Remove unneeded includes

Change-Id: Id299295784d6fcb04234b085566995bbd8a03d01
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/26734
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/northbridge/intel/x4x/gma.c

@@ -23,8 +23,6 @@
 #include <device/pci_ids.h>
 #include <string.h>
 #include <device/pci_ops.h>
-#include <cpu/x86/msr.h>
-#include <cpu/x86/mtrr.h>
 #include <commonlib/helpers.h>
 #include <cbmem.h>