rds: ib: update WR sizes when bringing up connection

Currently WR sizes are updated from rds_ib_sysctl_max_send_wr and
rds_ib_sysctl_max_recv_wr when a connection is shut down. As a result,
a connection being down while rds_ib_sysctl_max_send_wr or
rds_ib_sysctl_max_recv_wr are updated, will not update the sizes when
it comes back up.

Move resizing of WRs to rds_ib_setup_qp so that connections will be setup
with the most current WR sizes.

Signed-off-by: Dag Moxnes <dag.moxnes@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>