i40e: Add appropriate error message logged for incorrect duplex setting

Nothing logged in dmesg for attempting to set incorrect duplex.
Add appropriate error message logged for incorrect duplex setting.

Signed-off-by: Alicja Kowalska <alicjax.kowalska@intel.com>
Signed-off-by: Kamil Maziarz <kamil.maziarz@intel.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>