Support for match & set ICMPv6 reserved and options type fields

Support for match & set ICMPv6 reserved and options type fields

Currently OVS supports all ARP protocol fields as OXM match fields to
implement the relevant ARP procedures for IPv4. This includes support
for matching copying and setting ARP fields. In IPv6 ARP has been
replaced by ICMPv6 neighbor discovery (ND) procedures, neighbor
advertisement and neighbor solicitation.

The support for ICMPv6 fields in OVS is not complete for the use cases
equivalent to ARP in IPv4. OVS lacks support for matching, copying and
setting the “ND option type” and “ND reserved” fields. Without these user
cannot implement all ICMPv6 ND procedures for IPv6 support.

This commit adds additional OXM fields to OVS for ICMPv6 “ND option type“
and ICMPv6 “ND reserved” using the OXM extension mechanism. This allows
support for parsing these fields from an ICMPv6 packet header and extending
the OpenFlow protocol with specifications for these new OXM fields for
matching, copying and setting.

Signed-off-by: Vishal Deep Ajmera <vishal.deep.ajmera@ericsson.com>
Co-authored-by: Ashvin Lakshmikantha <ashvin.lakshmikantha@ericsson.com>
Signed-off-by: Ashvin Lakshmikantha <ashvin.lakshmikantha@ericsson.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>