blk-throttle: Free up policy node associated with deleted rule

If a rule is being deleted, free up associated policy node. Otherwise
that memory is leaked.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

@@ -1075,6 +1075,7 @@ static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
 
 	if (blkio_delete_rule_command(newpn)) {
 		blkio_policy_delete_node(pn);
+		kfree(pn);
 		spin_unlock_irq(&blkcg->lock);
 		goto update_io_group;
 	}