added avp_db db_url; credits go to Enrico

etc/ser.cfg

@@ -87,7 +87,7 @@ avpflags
 # ----------------- setting module-specific parameters ---------------
 
 # specify the path to you database here
-modparam("acc_db|auth_db|domain|gflags|usrloc|uri_db", "db_url", "mysql://ser:[email protected]/ser")
+modparam("acc_db|auth_db|avp_db|domain|gflags|usrloc|uri_db", "db_url", "mysql://ser:[email protected]/ser")
 
 # -- usrloc params --