Input: aiptek - do not try to export associated event device

Do not try to export via sysfs associated event device - it does not
work when evdev is a module that is loaded after aiptek; also it pokes
too deply into input core internals.

Userspace should rely on udev to set up permanent device name for
the tablet.

Signed-off-by: Rene van Paassen <rene.vanpaassen@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>