ccwgroup: move attributes to attribute group

commit dbdf1afc upstream.

Put sysfs attributes of ccwgroup devices in an attribute group to
ensure that these attributes are actually present when userspace
is notified via uevents.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>