linux-phytec-ti

backlight: Add support for the Avionic Design Xanthos backlight device.

This patch adds support for the backlight device found on Avionic Design
Xanthos-based boards.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>