scsi: scsi_transport_fc: Add comments to describe added 'rport' parameter

Note that there is no executable code altered by this patch.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507181446.aAoFiDm5-lkp@intel.com/


Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Link: https://lore.kernel.org/r/20250721164652.335716-1-emilne@redhat.com


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>