Please check if you have loaded ixl driver 1.6.8 or 1.6.10, you may execute below command to check, the sample output can be found in page 4 of this document - http://www.intel.com/content/www/us/en/embedded/products/networking/nvm-update-tool-freebsd-quick-usage-guide.html
The driver requirement is mentioned in page 11 of this document - http://www.intel.com/content/www/us/en/embedded/products/networking/xl710-ethernet-controller-feature-matrix.html?wapkw=xl710+feature+support+matrix
You need to have at least higher than 1.4.26 ixl driver to match version 5.05 NVM utility.
Please refer to the driver link at https://downloadcenter.intel.com/download/25160/Intel-Network-Adapter-Driver-for-PCI-E-Intel-40-Gigabit-Ethernet-Network-Connection-under-FreeBSD-
Please feel free to update me. Thanks.