HID: lenovo: Add ThinkPad 10 Ultrabook Keyboard fn_lock support

Add support for setting the Fn lock value of the ThinkPad 10 Ultrabook
Keyboard through sysfs, re-using the fn_lock sysfs attribute read/write
helpers from the existing ThinkPad Compact Keyboard with TrackPoint
support.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>