greybus: loopback: use the attribute groups, not group

We should use the attribute groups, not group, for the device, so
add and remove it.  No one should ever be updating a sysfs group for a
device, as that can be pretty dangerous if you don't duplicate _all_
existing attribute for that device, and I don't think we were doing that
here.
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/loopback.c

@@ -343,7 +343,7 @@ static int gb_loopback_connection_init(struct gb_connection *connection)
 
 	gb->connection = connection;
 	connection->private = gb;
-	retval = sysfs_update_group(&connection->dev.kobj, &loopback_group);
+	retval = sysfs_create_groups(&connection->dev.kobj, loopback_groups);
 	if (retval)
 		goto error;
 
@@ -372,7 +372,7 @@ static void gb_loopback_connection_exit(struct gb_connection *connection)
 
 	if (!IS_ERR_OR_NULL(gb->task))
 		kthread_stop(gb->task);
-	sysfs_remove_group(&connection->dev.kobj, &loopback_group);
+	sysfs_remove_groups(&connection->dev.kobj, loopback_groups);
 	kfree(gb);
 }