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>
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index c0d4a53..22a4994 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -243,3 +243,11 @@
 	help
 	  If you have a backlight driven by the ISINK and DCDC of a
 	  WM831x PMIC say y to enable the backlight driver for it.
+
+config BACKLIGHT_ADX
+	tristate "Avionic Design Xanthos Backlight Driver"
+	depends on BACKLIGHT_CLASS_DEVICE && ARCH_PXA_ADX
+	default y
+	help
+	  Say Y to enable the backlight driver on Avionic Design Xanthos-based
+	  boards.