Add Dual-FSP support (MemoryInitUpd/SiliconInitUpd)

Add Dual-FSP support (MemoryInitUpd/SiliconInitUpd)

Add FspUpdSignatureCheck() API in FspSecPlatformLib, so that FspSecCore can check if UPD data is valid in FSP API.
Add Set/GetFspMemoryInitUpdDataPointer() and Set/GetFspSiliconInitUpdDataPointer() API in FspCommonLib,
 so that core can set this UdpDataPointer and platform code may get UpdDataPointer easily.
Add UpdateMemSiUpdInitOffsetValue function in GenCfgOpt.py tool, so that the MemoryInitUpdOffset and SiUpdInitOffset is recorded.
Add missing EMBED comment in GenCfgOptUserManual.docx

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: "Yao, Jiewen" <Jiewen.Yao@intel.com>
Reviewed-by: "Mudusuru, Giri P" <giri.p.mudusuru@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18123 6f19259b-4bc3-4df7-8a09-765794883524