UefiCpuPkg PiSmmCpuDxeSmm: Update Ia32/MpFuncs.nasm

UefiCpuPkg PiSmmCpuDxeSmm: Update Ia32/MpFuncs.nasm

Use 16bit assembly code to replace hard code db.

In V2:
Add 0x67 prefix to far jump

When we enter protected mode, with the far jump still in big real mode,
the JMP instruction not only needs the 0x66 prefix (for 32-bit operand
size), but also the 0x67 prefix (for 32-bit address size). Use the a32
nasm modifier to enforce this.

This bug breaks S3 resume in the Ia32 + SMM_REQUIRE build of OVMF.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Liming Gao <liming.gao@intel.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>