To keep backward compatibility we used to leave attribute parsing
to the family if no policy is specified. This becomes tedious as
we move to more strict validation. Families must define reject all
policies if they don't want any attributes accepted.

Piggy back on the resv_start_op field as the switchover point.
AFAICT only ethtool has added new commands since the resv_start_op
was defined, and it has per-op policies so this should be a no-op.

Nonetheless the patch should still go into v6.1 for consistency.

Link: https://lore.kernel.org/all/20221019125745.3f2e7659@kernel.org/
Link: https://lore.kernel.org/r/20221021193532.1511293-1-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>