net/smc: wake up wr_reg_wait when terminating a link group

If a new connection with a new rmb is added to a link group, its
memory region is registered. If a link group is terminated, a pending
registration requires a wake up.

And consolidate setting of tx_flag peer_conn_abort in smc_lgr_terminate().

Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>