i40e/i40evf: remove redundant declarations of a variable and a function

Remove a variable declaration inside an if block hiding an existing
declaration at the start of the function.

Also remove a forward function declaration that is no longer needed due
to code re-organization.

Change-ID: I12954668b722718074949c93d74cd20eaacd93e4
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>