TTY: pty, release tty in all ptmx_open fail paths

Mistakenly, commit 64ba3dc3143d (tty: never hold BTM while getting
tty_mutex) switched one fail path in ptmx_open to not free the newly
allocated tty.

Fix that by jumping to the appropriate place. And rename the labels so
that it's clear what is going on there.

Introduced-in: v2.6.36-rc2
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: stable <stable@vger.kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/pty.c

@@ -686,15 +686,15 @@ static int ptmx_open(struct inode *inode, struct file *filp)
 
 	retval = devpts_pty_new(inode, tty->link);
 	if (retval)
-		goto out1;
+		goto err_release;
 
 	retval = ptm_driver->ops->open(tty, filp);
 	if (retval)
-		goto out2;
-out1:
+		goto err_release;
+
 	tty_unlock();
-	return retval;
-out2:
+	return 0;
+err_release:
 	tty_unlock();
 	tty_release(inode, filp);
 	return retval;