tls: delete useless removeListener call

onclose was never attached to 'end' so this call to remove this listener
is useless.  Delete it.

lib/tls.js

@@ -1373,7 +1373,6 @@ function pipe(pair, socket) {
 
   function onclose() {
     socket.removeListener('error', onerror);
-    socket.removeListener('end', onclose);
     socket.removeListener('timeout', ontimeout);
   }