[openib-general] return error when rdma_listen fails

[Sean Hefty]

Tom Tucker wrote:
> I think this makes sense for IB, however, for TCP based transports, we
> should share the port space with TCP.

My view is that the iWarp transport needs to provide the mapping from an 
RDMA_PS_TCP to the actual TCP port space, RDMA_PS_UDP to UDP, etc.  This is a 
function that should be part of the transport specific code, and not the general 
RDMA CM code.

How the RDMA CM handles a failure when one transport fails an operation, while 
another one succeeds is unclear.

- Sean