mfd: Use to_platform_device instead of container_of

Convert mfd_remove_devices_fn() to use to_platform_device()
instead of doing container_of().

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Acked-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index 0454be4..4dc861a 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -99,8 +99,7 @@
 
 static int mfd_remove_devices_fn(struct device *dev, void *unused)
 {
-	platform_device_unregister(
-			container_of(dev, struct platform_device, dev));
+	platform_device_unregister(to_platform_device(dev));
 	return 0;
 }