fbdev: radeonfb: Use backlight power constants

Replace FB_BLANK_ constants with their counterparts from the
backlight subsystem. The values are identical, so there's no
change in functionality or semantics.

Signed-off-by: Thomas Zimmermann <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Helge Deller <[e-mail]>
Reviewed-by: Jani Nikula <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/fbdev/aty/radeon_backlight.c

···
 		217 * FB_BACKLIGHT_MAX / MAX_RADEON_LEVEL);
 
 	bd->props.brightness = bd->props.max_brightness;
-	bd->props.power = FB_BLANK_UNBLANK;
+	bd->props.power = BACKLIGHT_POWER_ON;
 	backlight_update_status(bd);
 
 	printk("radeonfb: Backlight initialized (%s)\n", name);