issue: 4424775 Return EEXIST on duplicate setsockopt(TCP_ULP)

Fail setsockopt() instead of resetting the TLS offload state.
This change improve robustness and makes the behavior be compliant
to kernel.

Signed-off-by: Dmytro Podgornyi <[email protected]>

Author: pasis

src/core/sock/sockinfo_tcp.cpp

@@ -3758,6 +3758,13 @@ int sockinfo_tcp::tcp_setsockopt(int __level, int __optname, __const void *__opt
                         ret = -1;
                         break;
                     }
+                    ops = dynamic_cast<sockinfo_tcp_ops_tls *>(m_ops);
+                    if (ops) {
+                        si_tcp_loginfo("(TCP_ULP) val: tls, ULP is already TLS");
+                        errno = EEXIST;
+                        ret = -1;
+                        break;
+                    }
                     ops = new sockinfo_tcp_ops_tls(this);
                 }
             } else