Add the following class iteration functions for driver use:
	class_for_each_device
	class_find_device
	class_for_each_child
	class_find_child
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>