ACPI / video: Fix initial level validity test

When testing if the firmware's initial value is valid, we should use
the corrected level value instead of the raw value returned from
firmware.
Signed-off-by: NAaron Lu <aaron.lu@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/video.c

@@ -856,7 +856,7 @@ acpi_video_init_brightness(struct acpi_video_device *device)
 		 * or an index). Set the backlight to max_level in this case.
 		 */
 		for (i = 2; i < br->count; i++)
-			if (level_old == br->levels[i])
+			if (level == br->levels[i])
 				break;
 		if (i == br->count)
 			level = max_level;