UefiCpuPkg/PiSmmCpuDxeSmm: patch "gSmmInitStack" with PatchInstructionX86()
    
    Rename the variable to "gPatchSmmInitStack" so that its association with
    PatchInstructionX86() is clear from the declaration, change its type to
    UINT8, and patch it with PatchInstructionX86(). This lets us remove the
    binary (DB) encoding of some instructions in "SmmInit.nasm".
    
    The size of the patched source operand is (sizeof (UINTN)).
    
    Cc: Eric Dong <eric.dong@intel.com>
    Cc: Jiewen Yao <jiewen.yao@intel.com>
    Cc: Liming Gao <liming.gao@intel.com>
    Cc: Michael D Kinney <michael.d.kinney@intel.com>
    Cc: Ruiyu Ni <ruiyu.ni@intel.com>
    Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=866
    Contributed-under: TianoCore Contribution Agreement 1.1
    Signed-off-by: Laszlo Ersek <lersek@redhat.com>