macvtap: segmented packet is consumed

If GSO packet is segmented and its segments are properly queued,
we call consume_skb() instead of kfree_skb() to be drop monitor
friendly.

Fixes: 3e4f8b78

 ("macvtap: Perform GSO on forwarding path.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Vlad Yasevich <vyasevic@redhat.com>
Reviewed-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>