misc: use module_spi_driver

The _init and _exit functions can be replaced with the module_spi_driver
macro, which actually implements

static int __init drv_init(void)
{
	spi_register_driver(&driv_op);
	return 0;
}

module_init(drv_init);

static void __exit drv_exit(void)
{
	spi_unregister_driver(&driv_op);
}

module_exit(drv_exit);

Signed-off-by: Devendra Naga <develkernel412222@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>