spi: spi-au1550: replace platform_driver_probe to support deferred probing

Subsystems like pinctrl and gpio rightfully make use of deferred probing at
core level. Now, deferred drivers won't be retried if they don't have a .probe
function specified in the driver struct. Fix this driver to have that, so the
devices it supports won't get lost in a deferred probe.

Signed-off-by: Wolfram Sang <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

drivers/spi/spi-au1550.c

···
 MODULE_ALIAS("platform:au1550-spi");
 
 static struct platform_driver au1550_spi_drv = {
+	.probe = au1550_spi_probe,
 	.remove = au1550_spi_remove,
 	.driver = {
 		.name = "au1550-spi",
···
 			printk(KERN_ERR "au1550-spi: cannot add memory"
 					"dbdma device\n");
 	}
-	return platform_driver_probe(&au1550_spi_drv, au1550_spi_probe);
+	return platform_driver_register(&au1550_spi_drv);
 }
 module_init(au1550_spi_init);