soc/intel/skylake: Use real common code for VMX init

Use the common VMX implementation, and set IA32_FEATURE_CONTROL
lock bit per Kconfig *after* SGX is configured (as SGX also sets
bits on the IA32_FEATURE_CONTROL register).

As it is now correctly based on a Kconfig, the `VmxEnable` devicetree
setting vanishes.

Test: build/boot google/[chell,fizz], observe Virtualization enabled
under Windows 10 when VMX enabled and lock bit set.

Change-Id: Iea598cf74ba542a650433719f29cb5c9df700c0f
Signed-off-by: Nico Huber <nico.h@gmx.de>
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/29682
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/skylake/Kconfig

@@ -26,6 +26,7 @@ config CPU_SPECIFIC_OPTIONS
 	select CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM
 	select COLLECT_TIMESTAMPS
 	select COMMON_FADT
+	select CPU_INTEL_COMMON
 	select CPU_INTEL_FIRMWARE_INTERFACE_TABLE
 	select C_ENVIRONMENT_BOOTBLOCK
 	select FSP_M_XIP if MAINBOARD_USES_FSP2_0
@@ -65,7 +66,6 @@ config CPU_SPECIFIC_OPTIONS
 	select SOC_INTEL_COMMON_BLOCK_SMM
 	select SOC_INTEL_COMMON_BLOCK_SMM_IO_TRAP
 	select SOC_INTEL_COMMON_BLOCK_UART
-	select SOC_INTEL_COMMON_BLOCK_VMX
 	select SOC_INTEL_COMMON_PCH_BASE
 	select SOC_INTEL_COMMON_NHLT
 	select SOC_INTEL_COMMON_RESET