video, udlfb: Fix two build warnings about 'ignoring return value'

build warning:

...
drivers/video/udlfb.c:1590: warning: ignoring return value of ‘device_create_file’, declared with attribute warn_unused_result
drivers/video/udlfb.c:1592: warning: ignoring return value of ‘device_create_bin_file’, declared with attribute warn_unused_result
...

So add two checks to get rid of 'em.
Signed-off-by: NLiu Yuan <tailai.ly@taobao.com>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

drivers/video/udlfb.c

@@ -1587,10 +1587,19 @@ static int dlfb_usb_probe(struct usb_interface *interface,
 		goto error;
 	}
 
-	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
-		device_create_file(info->dev, &fb_device_attrs[i]);
+	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) {
+		retval = device_create_file(info->dev, &fb_device_attrs[i]);
+		if (retval) {
+			pr_err("device_create_file failed %d\n", retval);
+			goto err_del_attrs;
+		}
+	}
 
-	device_create_bin_file(info->dev, &edid_attr);
+	retval = device_create_bin_file(info->dev, &edid_attr);
+	if (retval) {
+		pr_err("device_create_bin_file failed %d\n", retval);
+		goto err_del_attrs;
+	}
 
 	pr_info("DisplayLink USB device /dev/fb%d attached. %dx%d resolution."
 			" Using %dK framebuffer memory\n", info->node,
@@ -1599,6 +1608,10 @@ static int dlfb_usb_probe(struct usb_interface *interface,
 			info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
 	return 0;
 
+err_del_attrs:
+	for (i -= 1; i >= 0; i--)
+		device_remove_file(info->dev, &fb_device_attrs[i]);
+
 error:
 	if (dev) {