netlink: specs: rt-link: add missing byte-order properties

A number of fields in the ip tunnels are lacking the big-endian
designation. I suspect this is not intentional, as decoding
the ports with the right endian seems objectively beneficial.

Fixes: 6ffdbb93 ("netlink: specs: rt_link: decode ip6tnl, vti and vti6 link attrs")
Fixes: 077b6022 ("doc/netlink/specs: Add sub-message type to rt_link family")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250603135357.502626-2-kuba@kernel.org


Signed-off-by: Paolo Abeni <pabeni@redhat.com>