fbdev: atyfb: 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: 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/atyfb_base.c

@@ -2219,13 +2219,7 @@ static int aty_bl_update_status(struct backlight_device *bd)
 {
 	struct atyfb_par *par = bl_get_data(bd);
 	unsigned int reg = aty_ld_lcd(LCD_MISC_CNTL, par);
-	int level;
-
-	if (bd->props.power != FB_BLANK_UNBLANK ||
-	    bd->props.fb_blank != FB_BLANK_UNBLANK)
-		level = 0;
-	else
-		level = bd->props.brightness;
+	int level = backlight_get_brightness(bd);
 
 	reg |= (BLMOD_EN | BIASMOD_EN);
 	if (level > 0) {