Device Model: do better cleanup on device removal

- make sure driverfs directory is removed after driver is detached and platform is notified (since they might have added files to it)
- Add release callback to struct device that is to be set by whoever allocated the device (e.g. the bus). 
This is the last thing called from put_device, so the owner of it can free the memory for the structure

drivers/base/core.c

@@ -96,9 +96,6 @@ void put_device(struct device * dev)
 	DBG("DEV: Unregistering device. ID = '%s', name = '%s'\n",
 	    dev->bus_id,dev->name);
 
-	/* remove the driverfs directory */
-	device_remove_dir(dev);
-
 	/* Notify the platform of the removal, in case they
 	 * need to do anything...
 	 */
@@ -112,6 +109,12 @@ void put_device(struct device * dev)
 	if (dev->driver && dev->driver->remove)
 		dev->driver->remove(dev,REMOVE_FREE_RESOURCES);
 
+	/* remove the driverfs directory */
+	device_remove_dir(dev);
+
+	if (dev->release)
+		dev->release(dev);
+
 	put_device(dev->parent);
 }
 

include/linux/device.h

@@ -92,6 +92,8 @@ struct device {
 					   being off. */
 
 	unsigned char *saved_state;	/* saved device state */
+
+	void	(*release)(struct device * dev);
 };
 
 static inline struct device *