Fix DUET X64 build error.

Signed-off-by: li-elvin
Reviewed-by: lgao4


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12277 6f19259b-4bc3-4df7-8a09-765794883524
diff --git a/DuetPkg/DuetPkgX64.dsc b/DuetPkg/DuetPkgX64.dsc
index f764b7a..59fec1a 100644
--- a/DuetPkg/DuetPkgX64.dsc
+++ b/DuetPkg/DuetPkgX64.dsc
@@ -101,6 +101,7 @@
   PlatformHookLib|MdeModulePkg/Library/BasePlatformHookLibNull/BasePlatformHookLibNull.inf

   SerialPortLib|MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.inf

   MtrrLib|UefiCpuPkg/Library/MtrrLib/MtrrLib.inf

+  LockBoxLib|MdeModulePkg/Library/LockBoxNullLib/LockBoxNullLib.inf

   

   #

   # To save size, use NULL library for DebugLib and ReportStatusCodeLib.