cpu/intel/common: Add/Use common function to set virtualization

Migrate duplicated enable_vmx() method from multiple CPUs to common
folder.  Add common virtualization option for CPUs which support it.

Note that this changes the default to enable virtualization on CPUs
that support it.

Change-Id: Ib110bed6c9f5508e3f867dcdc6f341fc50e501d1
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/17874
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins)

src/cpu/intel/common/common.h

@@ -0,0 +1,20 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _CPU_INTEL_COMMON_H
+#define _CPU_INTEL_COMMON_H
+
+void set_vmx(void);
+
+#endif