fbdev: radeon: Use backlight helper

Instead of retrieving the backlight brightness in struct
backlight_properties manually, and then checking whether the backlight
should be on at all, use backlight_get_brightness() which does all
this and insulates this from future changes.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Helge Deller <deller@gmx.de>

drivers/video/fbdev/aty/radeon_backlight.c

@@ -57,11 +57,7 @@ static int radeon_bl_update_status(struct backlight_device *bd)
 	 * backlight. This provides some greater power saving and the display
 	 * is useless without backlight anyway.
 	 */
-        if (bd->props.power != FB_BLANK_UNBLANK ||
-	    bd->props.fb_blank != FB_BLANK_UNBLANK)
-		level = 0;
-	else
-		level = bd->props.brightness;
+	level = backlight_get_brightness(bd);
 
 	del_timer_sync(&rinfo->lvds_timer);
 	radeon_engine_idle();