spi: butterfly: Switch to use module_parport_driver()

Switch to use module_parport_driver() to reduce boilerplate code.
Note, device_initcall() is a default for module_init().

Signed-off-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/spi/spi-butterfly.c

···
 	.detach =	butterfly_detach,
 	.devmodel = true,
 };
-
-static int __init butterfly_init(void)
-{
-	return parport_register_driver(&butterfly_driver);
-}
-device_initcall(butterfly_init);
-
-static void __exit butterfly_exit(void)
-{
-	parport_unregister_driver(&butterfly_driver);
-}
-module_exit(butterfly_exit);
+module_parport_driver(butterfly_driver);
 
 MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
 MODULE_LICENSE("GPL");