scsi: libfc: Do not login if the port is already started

When the port is already started we don't need to login; that
will only confuse the state machine.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Acked-by: Johannes Thumshirn <jth@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>