tipc: use kfree_skb() instead of kfree()

Use kfree_skb() instead of kfree() to free sk_buff.

Fixes: 0d051bf9

 ("tipc: make bearer packet filtering generic")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>