[SCSI] zfcp: resolve false usage of dd_data in fc_rport

The fc_rport structure reserves a reference where a LLD can put
information required in a situation where the fc transport class is
triggering LLD callbacks. The zfcp driver was using this variable
directly which is discouraged. This patch solves this issue by making
this reference unnecessary.  In addition the dev_loss_tmo callback is
removed, it is not required: zfcp does not access the fc_rport after
calling fc_remote_port_delete.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>