stream: removes unnecessary params

Removes the state param in the onFinished function
since it's never used within it.

lib/_stream_writable.js

@@ -619,7 +619,7 @@ Writable.prototype.end = function(chunk, encoding, cb) {
     if (err || state.finished)
       process.nextTick(cb, err);
     else
-      onFinished(this, state, cb);
+      onFinished(this, cb);
   }
 
   return this;
@@ -715,7 +715,7 @@ function onCorkedFinish(corkReq, state, err) {
 }
 
 // TODO(ronag): Avoid using events to implement internal logic.
-function onFinished(stream, state, cb) {
+function onFinished(stream, cb) {
   function onerror(err) {
     stream.removeListener('finish', onfinish);
     stream.removeListener('error', onerror);