scsi: libfc: use error code for fc_rport_error()

We only ever use the 'fp' argument for fc_rport_error() to
encapsulate the error code, so we can as well do away with that
and pass the error directly.

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>