EmulatorPkg/MpService: Fix a NULL reference

EmulatorPkg/MpService: Fix a NULL reference

when making a CreateEvent() to call CpuCheckAllAPsStatus(),
the Context parameter was NULL in CpuCheckAllAPsStatus(),
so we must not use the Context as the ProcessorData pointer.
and should recalculate it.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16183 6f19259b-4bc3-4df7-8a09-765794883524