tipc: use generic SKB list APIs to manage link receive queue

Use standard SKB list APIs associated with struct sk_buff_head to
manage link's receive queue to simplify its relevant code cemplexity.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>