scsi: scsi_transport_fc: Add dummy initiator role to rport

This patch allows scsi drivers that expose virturalized fibre channel
devices but that do not expose rports to successfully rescan the scsi
bus via echo "- - -" > /sys/class/scsi_host/hostX/scan.  Drivers can
create a pseudo rport and indicate FC_PORT_ROLE_FCP_DUMMY_INITIATOR as
the rport's role in fc_rport_identifiers. This insures that a valid
scsi_target_id is assigned to the newly created rport and it can meet
the requirements of fc_user_scan_tgt calling scsi_scan_target.

Signed-off-by: Cathy Avery <cavery@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>