SecurityPkg: Make time based AuthVariable update atomic

System may break during time based AuthVariable update, causing certdb inconsistent. 2 ways are used to ensure update atomic.
 1. Delete cert in certdb after variable is deleted
 2. Clean up certdb on variable initialization

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Chao Zhang <chao.b.zhang@intel.com>
Reviewed-by: Yao Jiewen <jiewen.yao@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17919 6f19259b-4bc3-4df7-8a09-765794883524

SecurityPkg/Library/AuthVariableLib/AuthServiceInternal.h

@@ -186,6 +186,22 @@ DeleteCertsFromDb (
   IN     EFI_GUID         *VendorGuid
   );
 
+/**
+  Clean up signer's certificates for common authenticated variable
+  by corresponding VariableName and VendorGuid from "certdb".
+  Sytem may break down during Timebased Variable update & certdb update,
+  make them inconsistent,  this function is called in AuthVariable Init to ensure 
+  consistency
+  
+  @retval  EFI_NOT_FOUND         Fail to find matching certs.
+  @retval  EFI_SUCCESS           Find matching certs and output parameters.
+
+**/
+EFI_STATUS
+CleanCertsFromDb (
+  VOID
+  );
+
 /**
   Filter out the duplicated EFI_SIGNATURE_DATA from the new data by comparing to the original data.