drm/panel: panel-sony-acx565akm: 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: Neil Armstrong <[e-mail]>
Cc: Jessica Zhang <[e-mail]>
Reviewed-by: Jessica Zhang <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/panel/panel-sony-acx565akm.c

···
 static int acx565akm_backlight_init(struct acx565akm_panel *lcd)
 {
 	struct backlight_properties props = {
-		.power = FB_BLANK_UNBLANK,
+		.power = BACKLIGHT_POWER_ON,
 		.type = BACKLIGHT_RAW,
 	};
 	int ret;