ipv6: Fix getHomeAddress() to properly iterate interfaces and find valid home address

The for loop contained an unconditional return in its body, so the loop
increment was never executed and it always operated on the first interface
only. Replace with direct access to the first interface using an if check.

Author: ZoltanBojthe

src/inet/networklayer/ipv6/Ipv6RoutingTable.cc

@@ -747,8 +747,11 @@ const Ipv6Address& Ipv6RoutingTable::getHomeAddress()
 {
     for (int i = 0; i < ift->getNumInterfaces(); ++i) {
         NetworkInterface *ie = ift->getInterface(i);
-
-        return ie->getProtocolData<Ipv6InterfaceData>()->getMNHomeAddress();
+        if (auto ipv6Data = ie->findProtocolData<Ipv6InterfaceData>()) {
+            const Ipv6Address& addr = ipv6Data->getMNHomeAddress();
+            if (!addr.isUnspecified())
+                return addr;
+        }
     }
 
     return Ipv6Address::UNSPECIFIED_ADDRESS;