i40e: fix link reporting

When querying the NVM for supported phy_types, on some firmware
versions, we were failing to actually fill out the phy_types which means
ethtool wouldn't report any link types.

Testing-hints:
Check 'ethtool <iface>' if you have the right (wrong?) firmware.
Without this patch, no link modes will be reported.

Signed-off-by: Alan Brady <alan.brady@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>