UefiCpuPkg/PiSmmCpu: Add 2 APIs in SmmCpuFeaturesLib.

UefiCpuPkg/PiSmmCpu: Add 2 APIs in SmmCpuFeaturesLib.

SmmCpuFeaturesCompleteSmmReadyToLock() is a hook point to
allow CPU specific code to do more registers setting after
the gEfiSmmReadyToLockProtocolGuid notification is completely
processed.

SmmCpuFeaturesAllocatePageTableMemory() is an API to allow
CPU to allocate a specific region for storing page tables.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: "Yao, Jiewen" <jiewen.yao@intel.com>
Reviewed-by: "Kinney, Michael D" <michael.d.kinney@intel.com>
Cc: "Fan, Jeff" <jeff.fan@intel.com>
Cc: "Kinney, Michael D" <michael.d.kinney@intel.com>
Cc: "Laszlo Ersek" <lersek@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18979 6f19259b-4bc3-4df7-8a09-765794883524