IntelFsp2WrapperPkg: Add variable initialization

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4595

Fix build error when remove "-Wno-sometimes-uninitialized" option,
Add variable "FspMultiPhaseApiOffset" initialization.

Cc: Nate DeSimone <[email protected]>
Cc: Star Zeng <[email protected]>
Cc: Chasel Chiu <[email protected]>
Cc: Duggapu Chinni B <[email protected]>
Cc: Ted Kuo <[email protected]>
Cc: Susovan Mohapatra <[email protected]>
Cc: James Lu <[email protected]>
Reviewed-by: Ashraf Ali S <[email protected]>
Reviewed-by: Chen Gang C <[email protected]>
Reviewed-by: Gua Guo <[email protected]>
Signed-off-by: Jason Hsu <[email protected]>

IntelFsp2WrapperPkg/Library/FspWrapperMultiPhaseProcessLib/PeiFspWrapperMultiPhaseProcessLib.c

@@ -80,6 +80,7 @@ CallFspMultiPhaseEntry (
   BOOLEAN                 IsVariableServiceRequest;
   FSP_MULTI_PHASE_PARAMS  *FspMultiPhaseParamsPtr;
 
+  FspMultiPhaseApiOffset   = 0;
   FspMultiPhaseParamsPtr   = (FSP_MULTI_PHASE_PARAMS *)FspMultiPhaseParams;
   IsVariableServiceRequest = FALSE;
   if ((FspMultiPhaseParamsPtr->MultiPhaseAction == EnumMultiPhaseGetVariableRequestInfo) ||