RDS: Stop supporting old cong map sending method

We now ask the transport to give us a rm for the congestion
map, and then we handle it normally. Previously, the
transport defined a function that we would call to send
a congestion map.

Convert TCP and loop transports to new cong map method.

Signed-off-by: Andy Grover <andy.grover@oracle.com>

net/rds/iw.c

@@ -264,7 +264,6 @@ struct rds_transport rds_iw_transport = {
 	.laddr_check		= rds_iw_laddr_check,
 	.xmit_complete		= rds_iw_xmit_complete,
 	.xmit			= rds_iw_xmit,
-	.xmit_cong_map		= NULL,
 	.xmit_rdma		= rds_iw_xmit_rdma,
 	.recv			= rds_iw_recv,
 	.conn_alloc		= rds_iw_conn_alloc,