UefiCpuPkg/PiSmmCpuDxeSmm: Correct CPUID leaf used to detect SMM mode

UefiCpuPkg/PiSmmCpuDxeSmm: Correct CPUID leaf used to detect SMM mode

Use Bit 29 of CPUID leaf CPUID_EXTENDED_CPU_SIG (0x80000001) to
determine the SMM save state mode.  The previous version of this
code used CPUID leaf CPUID_VERSION_INFO (0x00000001).

Cc: Jeff Fan <jeff.fan@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19503 6f19259b-4bc3-4df7-8a09-765794883524