i40e/i40evf: remove mismatched type warnings

i40e/i40evf: remove mismatched type warnings

Compiler reported several places where driver compared
signed and unsigned types.  Cast or change the types to remove
the warnings.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Orabug: 26785018
(cherry picked from commit b85c94b617c0004d1f2bd6ca32baa9132a6c2fe5)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Reviewed-by: Kyle Fortin <kyle.fortin@oracle.com>