UefiCpuPkg/SmmCpuFeaturesLib: drop obsolete API implementation

Commit 0426115b67 ("UefiCpuPkg: Remove unused API in
SmmCpuFeaturesLib.h", 2022-12-21) removed the declaration of the function
SmmCpuFeaturesAllocatePageTableMemory() from the "SmmCpuFeaturesLib.h"
library class header.

Remove the API's (null-)implementation from UefiCpuPkg/SmmCpuFeaturesLib
as well.

Build-tested with:

  build -a IA32 -a X64 -b NOOPT -p UefiCpuPkg/UefiCpuPkg.dsc -t GCC5

Cc: Eric Dong <eric.dong@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=4235
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Dun Tan <dun.tan@intel.com>

UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLibCommon.c

@@ -186,31 +186,3 @@ SmmCpuFeaturesCompleteSmmReadyToLock (
   )
 {
 }
-
-/**
-  This API provides a method for a CPU to allocate a specific region for storing page tables.
-
-  This API can be called more once to allocate memory for page tables.
-
-  Allocates the number of 4KB pages of type EfiRuntimeServicesData and returns a pointer to the
-  allocated buffer.  The buffer returned is aligned on a 4KB boundary.  If Pages is 0, then NULL
-  is returned.  If there is not enough memory remaining to satisfy the request, then NULL is
-  returned.
-
-  This function can also return NULL if there is no preference on where the page tables are allocated in SMRAM.
-
-  @param  Pages                 The number of 4 KB pages to allocate.
-
-  @return A pointer to the allocated buffer for page tables.
-  @retval NULL      Fail to allocate a specific region for storing page tables,
-                    Or there is no preference on where the page tables are allocated in SMRAM.
-
-**/
-VOID *
-EFIAPI
-SmmCpuFeaturesAllocatePageTableMemory (
-  IN UINTN  Pages
-  )
-{
-  return NULL;
-}