i40e: convert to use generic xdp_frame and xdp_return_frame API

Also convert driver i40e, which very recently got XDP_REDIRECT support
in commit d9314c47

 ("i40e: add support for XDP_REDIRECT").

V7: This patch got added in V7 of this patchset.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>