Document variables defined in struct attribute_group to ensure
correct usage.
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>