drivers/video/backlight/aat2870_bl.c: fix error checking for backlight_device_register

backlight_device_register() returns ERR_PTR() on error.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Jin Park <jinyoungp@nvidia.com>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/backlight/aat2870_bl.c

@@ -158,10 +158,10 @@ static int aat2870_bl_probe(struct platform_device *pdev)
 	props.type = BACKLIGHT_RAW;
 	bd = backlight_device_register("aat2870-backlight", &pdev->dev,
 				       aat2870_bl, &aat2870_bl_ops, &props);
-	if (!bd) {
+	if (IS_ERR(bd)) {
 		dev_err(&pdev->dev,
 			"Failed allocate memory for backlight device\n");
-		ret = -ENOMEM;
+		ret = PTR_ERR(bd);
 		goto out_kfree;
 	}