Add support for identityref data type

Change-Id: I369150b83d86a4c22fadf383ee011eee619a4c15
diff --git a/src/sysrepo_access.cpp b/src/sysrepo_access.cpp
index d514203..4e1ab4b 100644
--- a/src/sysrepo_access.cpp
+++ b/src/sysrepo_access.cpp
@@ -48,6 +48,12 @@
         return std::make_shared<sysrepo::Val>(value.m_value.c_str(), SR_BINARY_T);
     }
 
+    sysrepo::S_Val operator()(const identityRef_& value) const
+    {
+        auto res = value.m_prefix.value().m_name + ":" + value.m_value;
+        return std::make_shared<sysrepo::Val>(res.c_str(), SR_IDENTITYREF_T);
+    }
+
     sysrepo::S_Val operator()(const std::string& value) const
     {
         return std::make_shared<sysrepo::Val>(value.c_str());