scsi: libfc: reset exchange manager during LOGO handling

FC-LS mandates that we should invalidate all sequences before sending a
LOGO. And we should set the event to RPORT_EV_STOP when a LOGO request
has been received to signal that all exchanges are terminated.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Chad Dupuis <chad.dupuis@qlogic.com>
Tested-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>