ACPI / video: Fix initial level validity test

commit 9efa5e50 upstream.

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: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

drivers/acpi/video.c

@@ -836,7 +836,7 @@ 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)
 			level = max_level;