[openib-general] return error when rdma_listen fails

[Sean Hefty]

Pete Wyckoff wrote:
> Calling rdma_listen() on a cm_id bound to INADDR_ANY can fail, e.g.
> with EADDRINUSE, but report no error back to the user.  This patch
> fixes that by propagating the error.  Success occurs only if at
> least one of the possibly multiple devices in the system was able to
> listen.  In the case of multiple devices reporting errors on listen,
> only the first error value is returned.  iwarp branch.

There's a problem if the listen is done before any devices have been added to 
the system.  In this case, the listen should succeed.

- Sean