virtio_net: support inner header hash

[hengqiali]

When VIRTIO_NET_F_RSS is negotiated and the tunnel is used to
encapsulate the packets, the hash calculated using the outer header
of the receive packets is always fixed for the same flow packets,
i.e. they will be steered to the same receive queue.

We add a VIRTIO_NET_F_HASH_GRE_VXLAN_GENEVE_INNER feature bit and
related bitmasks in \field{hash_types}, which instructs the device
to calculate the hash using the inner headers of GRE, VXLAN or
GENEVE-encapsulated packets. Besides, \field{hash_report_tunnel} are
added to report packet type when calculating hash over the inner header.

https://lists.oasis-open.org/archives/virtio-dev/202212/msg00000.html

[hengqiali]

If the tunnel is used to encapsulate the packets, the hash calculated
using the outer header of the receive packets is always fixed for the
same flow packets, i.e. they will be steered to the same receive queue.

We add a tunnel feature bit VIRTIO_NET_F_HASH_TUNNEL and related bitmasks
in \field{hash_types}, which instructs the device to calculate the
hash using the inner headers of tunnel-encapsulated packets. Besides,
values in \field{hash_report_tunnel} are added to report tunnel types.

https://lists.oasis-open.org/archives/virtio-dev/202301/msg00023.html