[driver model] Remove extraneous class device release method.

What happens when you get a patch that does something an applied patch 
already does, but a little better, and merge it sloppily: You end up calling
the wrong function because you've defined equivalent methods in two places.

Bad Pat, Bad. 

include/linux/device.h

@@ -194,7 +194,6 @@ struct class_device {
 	void			* class_data;	/* class-specific data */
 
 	char	class_id[BUS_ID_SIZE];	/* unique to this class */
-	void	(*release)(struct class_device * class_dev);
 };
 
 static inline void *