UefiCpuPkg/PiSmmCpuDxeSmm: Use GDT/IDT saved in Smram.

UefiCpuPkg/PiSmmCpuDxeSmm: Use GDT/IDT saved in Smram.

Current implementation will copy GDT/IDT at SmmReadyToLock point
from ACPI NVS memory to Smram. Later at S3 resume phase, it restore
the memory saved in Smram to ACPI NVS. It can directly use GDT/IDT
saved in Smram instead of restore the original ACPI NVS memory.
This patch do this change.

Test Done:
  Do the OS boot and S3 resume test.

Cc: Laszlo Ersek <lersek@redhat.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: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>