IntelFsp2Pkg: FSP should not override IDT

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1265

FSP should not override IDT table when it is initialized
by boot loader. IDT should be re-initialized in FSP only
when it is invalid.
To mitigate temporary memory usage a PCD
PcdFspMaxInterruptSupported created for platform to decide
how many interrupts the FSP IDT table can support.

Test: Verified on internal platform and boots successfully.

Cc: Jiewen Yao <Jiewen.yao@intel.com>
Cc: Desimone Nathaniel L <nathaniel.l.desimone@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>

IntelFsp2Pkg/FspSecCore/FspSecCoreM.inf

@@ -62,6 +62,7 @@
   gIntelFsp2PkgTokenSpaceGuid.PcdTemporaryRamSize              ## CONSUMES
   gIntelFsp2PkgTokenSpaceGuid.PcdFspTemporaryRamSize           ## CONSUMES
   gIntelFsp2PkgTokenSpaceGuid.PcdFspHeapSizePercentage         ## CONSUMES
+  gIntelFsp2PkgTokenSpaceGuid.PcdFspMaxInterruptSupported      ## CONSUMES
 
 [Ppis]
   gEfiTemporaryRamSupportPpiGuid                              ## PRODUCES