neighbor: Disallow property changes

These do nothing and would cause the DBus entries to become
inconsistent.

Change-Id: I9bf815534c7098a22e0cc76c0c103b43de310837
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/neighbor.hpp b/src/neighbor.hpp
index 26859c3..4672726 100644
--- a/src/neighbor.hpp
+++ b/src/neighbor.hpp
@@ -88,6 +88,13 @@
      */
     void delete_() override;
 
+    using NeighborObj::ipAddress;
+    std::string ipAddress(std::string) override;
+    using NeighborObj::macAddress;
+    std::string macAddress(std::string) override;
+    using NeighborObj::state;
+    State state(State) override;
+
   private:
     /** @brief Parent Object. */
     EthernetInterface& parent;