virtio-net: Introduce hash report feature

The feature VIRTIO_NET_F_HASH_REPORT extends the
layout of the packet and requests the device to
calculate hash on incoming packets and report it
in the packet header.

Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
Link: https://lore.kernel.org/r/20200302115003.14877-4-yuri.benditovich@daynix.com


Signed-off-by: Michael S. Tsirkin <mst@redhat.com>