i40e: Fix to show correct Advertised Link Modes when link is down

When link is down, Advertised Link Modes was wrongly displaying full
supported link modes instead of Advertised link mode. Added conditional
checks in order to make sure correct Advertised link modes are
displayed when the link is down.

Change-ID: I8a61413f9ee174149c7a33157b5f0b0a8da9842d
Signed-off-by: Avinash Dayanand <avinash.dayanand@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>