UefiCpuPkg/ExceptionLib: Move global variable location

UefiCpuPkg/ExceptionLib: Move global variable location

Move some global variables location from PeiDxeSmmCpuException.c to
DxeCpuException.c and SmmCpuException.c. And remove some un-used global
vairables.

Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Jiewen Yao <jiewen.yao@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>