Driver core: add uevent vars for devices of a class

Devices converted from class_device to device should have
the same uevent keys as the original class_device had. We
search up the parents until we find the first bus device and
add the (already deprecated) PHYDEV* values.

Signed-off-by: Kay Sievers <kay.sievers@novell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>