i40e: Remove unnecessary prototypes

These functions don't need a prototype as they are defined
in the file before they are called.

Change-Id: Ie17ffad4a29a9c0df434c4ebc4681128a6095c65
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>