backlight: ipaq_micro: 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>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230106164856.1453819-4-steve@sk2.org

drivers/video/backlight/ipaq_micro_bl.c

@@ -16,17 +16,12 @@
 static int micro_bl_update_status(struct backlight_device *bd)
 {
 	struct ipaq_micro *micro = dev_get_drvdata(&bd->dev);
-	int intensity = bd->props.brightness;
+	int intensity = backlight_get_brightness(bd);
 	struct ipaq_micro_msg msg = {
 		.id = MSG_BACKLIGHT,
 		.tx_len = 3,
 	};
 
-	if (bd->props.power != FB_BLANK_UNBLANK)
-		intensity = 0;
-	if (bd->props.state & (BL_CORE_FBBLANK | BL_CORE_SUSPENDED))
-		intensity = 0;
-
 	/*
 	 * Message format:
 	 * Byte 0: backlight instance (usually 1)