UefiCpuPkg/MpInitLib: Move timeout delay to WakupAp()

UefiCpuPkg/MpInitLib: Move timeout delay to WakupAp()

After sending the 1st broadcast INIT-SIPI-SIPI, BSP will collect APs count after
one specified timeout delay. However, WakupAp() will restore reset vector
immediately after sending 1st broadcast INIT-SIPI-SIPI. Some processors may not
complete executing reset vector code.

This fix is to move MicroSecondDelay() from CollectProcessorCount() to the place
that is after sending 1st broadcast INIT-SIPI-SIPI and before FreeResetVector()
in WakupAp().

Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>