network: Correct some issues that prevent TCP from working correctly when both IPv4 and IPv6 are enabled.

net/socket/send.c

@@ -255,6 +255,7 @@ ssize_t psock_send(FAR struct socket *psock, FAR const void *buf, size_t len,
       set_errno(-ret);
       ret = ERROR;
     }
+
   return ret;
 }
 

net/tcp/tcp_input.c

@@ -285,7 +285,7 @@ static void tcp_input(FAR struct net_driver_s *dev, uint8_t domain,
         }
     }
 
-  nwarn("WARNING: Old packet .. reset\n");
+  nwarn("WARNING: SYN with no listener (or old packet) .. reset\n");
 
   /* This is (1) an old duplicate packet or (2) a SYN packet but with
    * no matching listener found.  Send RST packet in either case.

net/tcp/tcp_send_buffered.c

@@ -243,7 +243,7 @@ static inline void send_ipselect(FAR struct net_driver_s *dev,
       /* Select the IPv6 domain */
 
       DEBUGASSERT(conn->domain == PF_INET6);
-      tcp_ipv4_select(dev);
+      tcp_ipv6_select(dev);
     }
 }
 #endif

net/tcp/tcp_send_unbuffered.c

@@ -194,7 +194,7 @@ static inline void tcpsend_ipselect(FAR struct net_driver_s *dev,
       /* Select the IPv6 domain */
 
       DEBUGASSERT(conn->domain == PF_INET6);
-      tcp_ipv4_select(dev);
+      tcp_ipv6_select(dev);
     }
 }
 #endif