drop repeating record type generate*Rrset in rrset-factory

Change-Id: I64f18cb5f08febbbeccaa66b10b7a46a06a4bc76
diff --git a/src/mgmt/management-tool.cpp b/src/mgmt/management-tool.cpp
index b0bd7b4..d4d64e1 100644
--- a/src/mgmt/management-tool.cpp
+++ b/src/mgmt/management-tool.cpp
@@ -284,7 +284,7 @@
       continue;
     }
 
-    Rrset authRr = zoneRrFactory.generateAuthRrset(prefix, label::NS_RR_TYPE,
+    Rrset authRr = zoneRrFactory.generateAuthRrset(prefix,
                                                    VERSION_USE_UNIX_TIMESTAMP, authTtl);
     NDNS_LOG_INFO("Adding NDNS_AUTH " << authRr);
     m_dbMgr.insert(authRr);