i40e: fix reading LLDP configuration

Previous method for reading LLDP config was based on hard-coded
offsets. It happened to work, because of structured architecture of
the NVM memory. In the new approach, known as FLAT, we need to
calculate the absolute address, instead of using relative values.
Needed defines for memory location were added.

Signed-off-by: Mariusz Stachura <mariusz.stachura@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>