drm/tilcdc: 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: Jyri Sarha <[e-mail]>
Cc: Tomi Valkeinen <[e-mail]>
Reviewed-by: Tomi Valkeinen <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/tilcdc/tilcdc_panel.c

···
 
 	if (backlight) {
 		backlight->props.power = mode == DRM_MODE_DPMS_ON ?
-					 FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
+					 BACKLIGHT_POWER_ON : BACKLIGHT_POWER_OFF;
 		backlight_update_status(backlight);
 	}