backlight: ktd253: Support KTD259

The KTD259 works just like KTD253 so add this compatible
to the driver.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/video/backlight/ktd253-backlight.c

@@ -173,6 +173,7 @@ static int ktd253_backlight_probe(struct platform_device *pdev)
 
 static const struct of_device_id ktd253_backlight_of_match[] = {
 	{ .compatible = "kinetic,ktd253" },
+	{ .compatible = "kinetic,ktd259" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, ktd253_backlight_of_match);