This patch add support for lvds backlight on i.CoreM6 QDL
variant boards.

Cc: Domenico Acri <domenico.acri@engicam.com>
Cc: Matteo Lisi <matteo.lisi@engicam.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>