IntelFsp2Pkg : Set FSP-I upd data pointer to NULL as default

FSP-I upd data pointer should be set NULL as default, it could
avoid other code to use it before it was set with correct pointer.

Signed-off-by: Hongbin1 Zhang <hongbin1.zhang@intel.com>
Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Duggapu Chinni B <chinni.b.duggapu@intel.com>
Cc: Ted Kuo <ted.kuo@intel.com>
Cc: Ashraf Ali S <ashraf.ali.s@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>

IntelFsp2Pkg/FspSecCore/SecFsp.c

@@ -174,6 +174,7 @@ FspGlobalDataInit (
   SetFspUpdDataPointer (FspmUpdDataPtr);
   SetFspMemoryInitUpdDataPointer (FspmUpdDataPtr);
   SetFspSiliconInitUpdDataPointer (NULL);
+  SetFspSmmInitUpdDataPointer (NULL);
 
   //
   // Initialize OnSeparateStack value.