nvmf_free_qpair() now closes the underlying transport (e.g. socket for
the TCP transport) when freeing a qpair.
nvmf_close_qpair() can be used to force-close the underlying transport
connection without freeing the queue pair.
The nvmf_accept and nvmf_connect helper routines also take ownership
of the transport specified in the qpair parameters and close it if an
error occurs connecting and/or validating a new qpair.
This permits consumers to avoid tracking the underlying transport and
managing its life cycle in parallel with the qpair.