nlsr: avoid deprecated prefix registration APIs

refs #2932

Change-Id: Id874d40d3b6209bedc6f92a44b5c49eb9ed31efe
diff --git a/src/nlsr.hpp b/src/nlsr.hpp
index 9d6679f..20adfb2 100644
--- a/src/nlsr.hpp
+++ b/src/nlsr.hpp
@@ -377,7 +377,7 @@
   security::CertificateStore m_certStore;
   Validator m_validator;
   ndn::KeyChain m_keyChain;
-  ndn::Name m_defaultIdentity;
+  ndn::security::SigningInfo m_signingInfo;
   ndn::Name m_defaultCertName;
   update::PrefixUpdateProcessor m_prefixUpdateProcessor;