RDMA/cxgb3: Add set_tcb_rpl_handler

As of commit 6cdbd77e

 ("cxgb3 - missing CPL hanler and register
setting."), the cxgb3 ethernet NIC driver no longer handles SET_TCB
replies, so we need to do it in the iWARP driver.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Acked-by: Divy Le Ray <divy@chelsio.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>