cpu/intel/fsp_model_406dx: code cleanup

Code cleanup requested in commit 09670265 -
"cpu/intel: Add fsp version of model 406dx (Rangeley / Atom C2000)"

- add guard statements to chip.h
- remove excessive includes
- whitespace cleanup
- add an IS_ENABLED

Change-Id: Iaa85bd66953df015f083b23f6fd32949bcfd17bc
Signed-off-by: Martin Roth <martin.roth@se-eng.com>
Reviewed-on: http://review.coreboot.org/6599
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>

src/cpu/intel/fsp_model_406dx/chip.h

@@ -17,6 +17,9 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  */
 
+#ifndef CPU_FSP_MODEL406DX_CHIP_H
+#define CPU_FSP_MODEL406DX_CHIP_H
+
 /* Magic value used to locate this chip in the device tree */
 #define SPEEDSTEP_APIC_MAGIC 0xACAC
 
@@ -31,3 +34,5 @@ struct cpu_intel_fsp_model_406dx_config {
 	int c2_acpower;		/* ACPI C2 on AC Power */
 	int c3_acpower;		/* ACPI C3 on AC Power */
 };
+
+#endif /* CPU_FSP_MODEL406DX_CHIP_H */

src/cpu/intel/fsp_model_406dx/model_406dx.h

@@ -110,4 +110,4 @@ int cpu_config_tdp_levels(void);
 #endif
 #endif
 
-#endif
+#endif /* _CPU_INTEL_MODEL_406DX_H */

src/cpu/intel/fsp_model_406dx/model_406dx_init.c

@@ -22,19 +22,13 @@
  */
 
 #include <console/console.h>
-#include <device/device.h>
 #include <device/pci.h>
-#include <string.h>
-#include <arch/acpi.h>
 #include <cpu/cpu.h>
 #include <cpu/x86/mtrr.h>
 #include <cpu/x86/msr.h>
 #include <cpu/x86/lapic.h>
-#include <cpu/intel/speedstep.h>
-#include <cpu/intel/turbo.h>
 #include <cpu/x86/cache.h>
 #include <cpu/x86/name.h>
-#include <pc80/mc146818rtc.h>
 #include "model_406dx.h"
 #include "chip.h"
 
@@ -42,7 +36,7 @@ static void enable_vmx(void)
 {
 	struct cpuid_result regs;
 	msr_t msr;
-	int enable = CONFIG_ENABLE_VMX;
+	int enable = IS_ENABLED(CONFIG_ENABLE_VMX);
 
 	regs = cpuid(1);
 	/* Check that the VMX is supported before reading or writing the MSR. */