nvme-fc: require target or discovery role for fc-nvme targets

In order to create an association, the remoteport must be
serving either a target role or a discovery role.

Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>