IntelSiliconPkg IntelVTdDxe: Do not SetupVtd again

Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Star Zeng <star.zeng@intel.com>
Tested-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c

@@ -412,6 +412,9 @@ AcpiNotificationFunc (
 
   Status = GetDmarAcpiTable ();
   if (EFI_ERROR (Status)) {
+    if (Status == EFI_ALREADY_STARTED) {
+      gBS->CloseEvent (Event);
+    }
     return;
   }
   SetupVtd ();