i40e: Cleaning up missing null-terminate in conjunction with strncpy

Replacing strncpy with strlcpy to avoid strings that lacks null terminate.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Tested-By: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>