UefiCpuPkg/PiSmmCpuDxeSmm: Remove MTRRs from PSD structure

https://bugzilla.tianocore.org/show_bug.cgi?id=277

All CPUs use the same MTRR settings.  Move MTRR settings
from a field in the PROCESSOR_SMM_DESCRIPTOR structure into
a module global variable.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Cc: Feng Tian <feng.tian@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>
Reviewed-by: Feng Tian <feng.tian@intel.com>

UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h

@@ -380,7 +380,7 @@ typedef struct {
   UINT16                            Reserved11;             // Offset 0x50
   UINT16                            Reserved12;             // Offset 0x52
   UINT32                            Reserved13;             // Offset 0x54
-  UINT64                            MtrrBaseMaskPtr;        // Offset 0x58
+  UINT64                            Reserved14;             // Offset 0x58
 } PROCESSOR_SMM_DESCRIPTOR;