staging: unisys: visorinput: Add module_driver driver registration

1. Remove module_init()/module_exit() macroes and
visorbus_register_visor_driver/visorbus_unregister_visor_driver
functions.
2. Replace with a short module_driver macro

Signed-off-by: Alex Briskin <br.shurik@gmail.com>
Acked-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>