UefiCpuPkg/PiSmmCpuDxeSmm: Refine code to avoid duplicated code.

UefiCpuPkg/PiSmmCpuDxeSmm: Refine code to avoid duplicated code.

V2:
  Change function parameter to avoid touch global info in function.
  Enhance function name, make it more user friendly

V1:
  Refine code to avoid duplicate code to set processor register.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>