TTY: fix fail path in tty_open

When tty_add_file fails we omit to clean up. Fix that by calling
tty_release appropriatelly.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>