i40e: Removing unnecessary code which caused supported link mode bug

Removing this code which wasn't allowing 100BaseT to show up in the supported
link modes for 10GBaseT PHYs.

Change-ID: Iada2eafa7ef6b4bac9a2a1380ff533ae5de51e1d
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>