We must not free the possible_values string before we have called
sysfs_remove_group(kobj, &tlmi_attr_group) otherwise there is a race
where a sysfs read of possible_values could reference the free-ed
memory.

Move the kfree(setting->possible_values) together with the free of the
actual tlmi_attr_setting struct to avoid this race.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>