pscsi: finish cmd processing from pscsi_req_done

This patch performs the pscsi_transport_complete operations from
pscsi_req_done. It looks like the only difference the transport_complete
callout provides is that it is called under t_state_lock which seems to
only be needed for the SCF_TRANSPORT_TASK_SENSE bit handling. We can
now use transport_copy_sense_to_cmd to handle the se_cmd sense bits, and
we can then drop the code where we have to copy the request info to
the pscsi_plugin_task for transport_complete use.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>