Fixes the lack of output on the LVDS panel of the Lenovo U160.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=31596Reported-and-tested-by: Dirk Gouders <gouders@et.bocholt.fh-gelsenkirchen.de>
Cc: stable@kernel.org
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>