spi: free children in spi_unregister_master, not siblings

introduced by 49dce689 ("spi doesn't need class_device") and bad-fixed
by 350d0076 ("spi: fix double-free on spi_unregister_master"),
spi_unregister_master would previously device_unregister all of the spi
master's siblings (instead of its children). hilarity ensues.

fix it to unregister children.
Signed-off-by: David Lamparter <equinox@diac24.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/spi/spi.c

@@ -554,10 +554,8 @@ int spi_register_master(struct spi_master *master)
 EXPORT_SYMBOL_GPL(spi_register_master);
 
 
-static int __unregister(struct device *dev, void *master_dev)
+static int __unregister(struct device *dev, void *null)
 {
-	/* note: before about 2.6.14-rc1 this would corrupt memory: */
-	if (dev != master_dev)
 	spi_unregister_device(to_spi_device(dev));
 	return 0;
 }
@@ -576,8 +574,7 @@ void spi_unregister_master(struct spi_master *master)
 {
 	int dummy;
 
-	dummy = device_for_each_child(master->dev.parent, &master->dev,
-					__unregister);
+	dummy = device_for_each_child(&master->dev, NULL, __unregister);
 	device_unregister(&master->dev);
 }
 EXPORT_SYMBOL_GPL(spi_unregister_master);