hardware offload support for openvswitch

In Kernel 4.8 we introduced Traffic Control (TC see [1]) hardware offloads
framework for SR-IOV VFs which allows us to configure the NIC [2].
Subsequent OVS patches [3] allow us to use the TC framework
to offload OVS datapath rule

This patch adds the VIF_TYPE_OVS_ACCELERATION
to portbindings

[1] http://netdevconf.org/1.2/papers/efraim-gerlitz-sriov-ovs-final.pdf
[2] https://patchwork.ozlabs.org/patch/738176/
[3] https://mail.openvswitch.org/pipermail/ovs-dev/2017-April/330606.html

Partial-Bug: #1627987

Change-Id: I41c0a44ebe5e886c689de9fbd7fadb9cb549dc68

neutron_lib/api/definitions/portbindings.py

@@ -87,6 +87,10 @@ VIF_TYPE_BINDING_FAILED = 'binding_failed'
 VIF_TYPE_DISTRIBUTED = 'distributed'
 VIF_TYPE_OVS = 'ovs'
 VIF_TYPE_BRIDGE = 'bridge'
+# - ovs-acceleration: The ovs acceleration interface type is a SR-IOV hostdev
+#                     interface which support switchdev mode provided by
+#                     kernel 4.8.
+VIF_TYPE_OVS_ACCELERATION = 'ovs_acceleration'
 VIF_TYPE_OTHER = 'other'
 VIF_TYPE_TAP = 'tap'
 # vif_type_macvtap: Tells Nova that the macvtap vif_driver should be used to

releasenotes/notes/add_vif_type_ovs_acceleration-0f983fa70c6d7519.yaml

@@ -0,0 +1,3 @@
+---
+features:
+  - Add new vif type ``VIF_TYPE_OVS_ACCELERATION`` to portbindings.