sockets: Make IPv6 only netconn type IPv6 aware

src/api/sockets.c

@@ -184,7 +184,7 @@ static void sockaddr_to_ipaddr_port(const struct sockaddr *sockaddr, ip_addr_t *
         IP6ADDR_PORT_TO_SOCKADDR((struct sockaddr_in6*)(void*)(sockaddr), ip_2_ip6(ipaddr), port)
 #define SOCKADDR_TO_IPADDR_PORT(sockaddr, ipaddr, port) \
         SOCKADDR6_TO_IP6ADDR_PORT((const struct sockaddr_in6*)(const void*)(sockaddr), ipaddr, port)
-#define DOMAIN_TO_NETCONN_TYPE(domain, netconn_type) (netconn_type)
+#define DOMAIN_TO_NETCONN_TYPE(domain, type) ((enum netconn_type)((type) | NETCONN_TYPE_IPV6))
 #else /*-> LWIP_IPV4: LWIP_IPV4 && LWIP_IPV6 */
 #define IS_SOCK_ADDR_LEN_VALID(namelen)  ((namelen) == sizeof(struct sockaddr_in))
 #define IS_SOCK_ADDR_TYPE_VALID(name)    ((name)->sa_family == AF_INET)