REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1280 When copying IDT table in SecMain, the pointer might be NULL so added the check to fix it. 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>