Merge branch 'netlink-specs-add-ynl-spec-for-ovs_flow'

Donald Hunter says:

====================
netlink: specs: add ynl spec for ovs_flow

Add a ynl specification for ovs_flow. The spec is sufficient to dump ovs
flows but some attrs have been left as binary blobs because ynl doesn't
support C arrays in struct definitions yet.

Patches 1-3 add features for genetlink-legacy specs
Patch 4 is the ovs_flow netlink spec
====================

Link: https://lore.kernel.org/r/20230527133107.68161-1-donald.hunter@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>