scsi: libfc: use configured lport R_A_TOV

We should be using the configured R_A_TOV value when sending the
exchange.

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>