Permit IPv6 Address Router Advertisement values to be changed

The current IPv6 Address Router Advertisement value written to the
configuration file is always 'false'. This allows DBus to update the
configuration file with either boolean value.

Tested:
Used dbus-send to modify the IPv6AcceptRA property.  Confirmed the
/etc/systemd/network/00-bmc-ethx.network file updated.

Change-Id: Ia57ca80122411aabf84afb7334d70b5b7740bd28
Signed-off-by: Johnathan Mantey <johnathanx.mantey@intel.com>
diff --git a/ethernet_interface.hpp b/ethernet_interface.hpp
index 3935390..e48fddb 100644
--- a/ethernet_interface.hpp
+++ b/ethernet_interface.hpp
@@ -156,6 +156,16 @@
      */
     std::string mACAddress(std::string value) override;
 
+    /** @brief get the IPv6AcceptRA flag from the network configuration file
+     *
+     */
+    bool getIPv6AcceptRAFromConf();
+
+    /** @brief check conf file for Router Advertisements
+     *
+     */
+    bool iPv6AcceptRA(bool value) override;
+
     /** @brief sets the NTP servers.
      *  @param[in] value - vector of NTP servers.
      */