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)
diff --git a/src/soc/intel/broadwell/Kconfig b/src/soc/intel/broadwell/Kconfig
index 75cd831..01bcaf1 100644
--- a/src/soc/intel/broadwell/Kconfig
+++ b/src/soc/intel/broadwell/Kconfig
@@ -44,6 +44,7 @@
 	select HAVE_INTEL_FIRMWARE
 	select SOC_INTEL_COMMON_ACPI_WAKE_SOURCE
 	select HAVE_SPI_CONSOLE_SUPPORT
+	select CPU_INTEL_COMMON
 
 config BOOTBLOCK_CPU_INIT
 	string
@@ -57,7 +58,6 @@
 	string
 	default "soc/intel/broadwell/bootblock/pch.c"
 
-
 config MMCONF_BASE_ADDRESS
 	hex
 	default 0xf0000000