xen-blkfront: free resources if xlvbd_alloc_gendisk fails

Current code forgets to free resources in the failure path of
xlvbd_alloc_gendisk(), this patch fix it.
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/block/xen-blkfront.c

@@ -2442,7 +2442,7 @@ static void blkfront_connect(struct blkfront_info *info)
 	if (err) {
 		xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
 				 info->xbdev->otherend);
-		return;
+		goto fail;
 	}
 
 	xenbus_switch_state(info->xbdev, XenbusStateConnected);
@@ -2455,6 +2455,11 @@ static void blkfront_connect(struct blkfront_info *info)
 	device_add_disk(&info->xbdev->dev, info->gd);
 
 	info->is_ready = 1;
+	return;
+
+fail:
+	blkif_free(info, 0);
+	return;
 }
 
 /**