UefiCpuPkg: Use CpuPageTableLib to convert SMM paging attribute.

Simplify the ConvertMemoryPageAttributes API to convert paging
attribute by CpuPageTableLib. In the new API, it calls
PageTableMap() to update the page attributes of a memory range.
With the PageTableMap() API in CpuPageTableLib, we can remove
the complicated page table manipulating code.

Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>

UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf

@@ -100,6 +100,7 @@
   SmmCpuFeaturesLib
   PeCoffGetEntryPointLib
   PerformanceLib
+  CpuPageTableLib
 
 [Protocols]
   gEfiSmmAccess2ProtocolGuid               ## CONSUMES