Merge branch 'ethtool-netlink-interface-preliminary-part'

Michal Kubecek says:

====================
ethtool netlink interface, preliminary part

As Jakub Kicinski suggested in ethtool netlink v7 discussion, this
submission consists only of preliminary patches which raised no objections;
first four patches already have Acked-by or Reviewed-by.

- patch 1 exposes permanent hardware address (as shown by "ethtool -P")
  via rtnetlink
- patch 2 is renames existing netlink helper to a better name
- patch 3 and 4 reorganize existing ethtool code (no functional change)
- patch 5 makes the table of link mode names available as an ethtool string
  set (will be needed for the netlink interface)

Once we get these out of the way, v8 of the first part of the ethtool
netlink interface will follow.

Changes from v2 to v3: fix SPDX licence identifiers (patch 3 and 5).

Changes from v1 to v2: restore build time check that all link modes have
assigned a name (patch 5).
====================

Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>