tipc: a couple of cleanups

- We remove the 'reclaiming' member list in struct tipc_group, since
  it doesn't serve any purpose.

- We simplify the GRP_REMIT_MSG branch of tipc_group_protocol_rcv().

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