LWIP::get_ipv6_addr fixed to avoid returning NULL even if only linklocal adress exits.

Author: tymoteuszblochmobica

features/lwipstack/lwip_tools.cpp

@@ -92,6 +92,12 @@ const ip_addr_t *LWIP::get_ipv6_addr(const struct netif *netif)
             return netif_ip_addr6(netif, i);
         }
     }
+
+    for (int i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
+        if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i))) {
+            return netif_ip_addr6(netif, i);
+        }
+    }
 #endif
     return NULL;
 }