Fix the issue that FTW driver fail to reclaim WorkSpace.

Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Hengyan Tao <hengyan.tao@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13732 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c

@@ -209,6 +209,8 @@ GetFvbCountAndBuffer (
   *NumberHandles = BufferSize / sizeof(EFI_HANDLE);
   if (EFI_ERROR(Status)) {
     *NumberHandles = 0;
+    FreePool (*Buffer);
+    *Buffer = NULL;
   }
 
   return Status;