The backlight class is used to create userspace handles for
setting the OLED contrast.
Signed-off-by: Thomas Niederprüm <niederp@physik.uni-kl.de> Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>