UefiCpuPkg/PiSmmCpuDxeSmm: patch "gSmiCr3" with PatchInstructionX86()
    
    Rename the variable to "gPatchSmiCr3" so that its association with
    PatchInstructionX86() is clear from the declaration, change its type to
    X86_ASSEMBLY_PATCH_LABEL, and patch it with PatchInstructionX86(). This
    lets us remove the binary (DB) encoding of some instructions in
    "SmiEntry.nasm".
    
    Cc: Eric Dong <eric.dong@intel.com>
    Cc: Michael D Kinney <michael.d.kinney@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>
    Reviewed-by: Liming Gao <liming.gao@intel.com>