TTY: hso, do not set TTY MAGIC

It is set in alloc_tty_driver already. No need to re-set.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Jan Dumon <j.dumon@option.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>