UefiCpuPkg/MpInitLib: Implementation of MpInitLibEnableDisableAP()

v4:
  1. Simply the internal function MpInitLibEnableDisableAP()'s function
     header due to it is duplicated with MpInitLibEnableDisableAP().
v3:
  1. Use CamelCase for mCheckAllAPsEvent, mStopCheckAllApsStatus.

Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Giri P Mudusuru <giri.p.mudusuru@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Michael Kinney <michael.d.kinney@intel.com>

UefiCpuPkg/Library/MpInitLib/PeiMpLib.c

@@ -604,7 +604,7 @@ MpInitLibEnableDisableAP (
   IN  UINT32                    *HealthFlag OPTIONAL
   )
 {
-  return EFI_UNSUPPORTED;
+  return EnableDisableApWorker (ProcessorNumber, EnableAP, HealthFlag);
 }