UefiCpuPkg/CpuCommonFeaturesLib: Support X2APIC enable

Current X2APIC is enabled in MpInitLib (used by CpuMpPei and CpuDxe) to follow
SDM suggestion. That means we only enable X2APIC if we found there are any
initial CPU ID value >= 255.

This patch is to provide one chance for platform to enable X2APIC even there is
no any initial CPU ID value >= 255.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>

UefiCpuPkg/Library/CpuCommonFeaturesLib/CpuCommonFeaturesLib.c

@@ -211,7 +211,7 @@ CpuCommonFeaturesLibConstructor (
   if (IsCpuFeatureSupported (CPU_FEATURE_X2APIC)) {
     Status = RegisterCpuFeature (
                "X2Apic",
-               NULL,
+               X2ApicGetConfigData,
                X2ApicSupport,
                X2ApicInitialize,
                CPU_FEATURE_X2APIC,