uio: add missing error codes

My static checker complains that "ret" could be uninitialized at the
end, which is true but it's more likely that it would be set to zero.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/uio/uio.c

@@ -271,12 +271,16 @@ static int uio_dev_add_attributes(struct uio_device *idev)
 			map_found = 1;
 			idev->map_dir = kobject_create_and_add("maps",
 							&idev->dev->kobj);
-			if (!idev->map_dir)
+			if (!idev->map_dir) {
+				ret = -ENOMEM;
 				goto err_map;
+			}
 		}
 		map = kzalloc(sizeof(*map), GFP_KERNEL);
-		if (!map)
+		if (!map) {
+			ret = -ENOMEM;
 			goto err_map_kobj;
+		}
 		kobject_init(&map->kobj, &map_attr_type);
 		map->mem = mem;
 		mem->map = map;
@@ -296,12 +300,16 @@ static int uio_dev_add_attributes(struct uio_device *idev)
 			portio_found = 1;
 			idev->portio_dir = kobject_create_and_add("portio",
 							&idev->dev->kobj);
-			if (!idev->portio_dir)
+			if (!idev->portio_dir) {
+				ret = -ENOMEM;
 				goto err_portio;
+			}
 		}
 		portio = kzalloc(sizeof(*portio), GFP_KERNEL);
-		if (!portio)
+		if (!portio) {
+			ret = -ENOMEM;
 			goto err_portio_kobj;
+		}
 		kobject_init(&portio->kobj, &portio_attr_type);
 		portio->port = port;
 		port->portio = portio;