As of upstream kernel v4.18-rc8.

Note that we name the features like they are called in ethtool's
ioctl API ETH_SS_FEATURES.

Except, for features like "tx-gro", which ethtool utility aliases
as "gro". So, for those features where ethtool has a built-in,
alternative name, we prefer the alias.

And again, note that a few aliases of ethtool utility ("sg", "tso", "tx")
actually affect more than one underlying kernel feature.

Note that 3 kernel features which are announced via ETH_SS_FEATURES are
explicitly exluded because kernel marks them as "never_changed":

    #define NETIF_F_NEVER_CHANGE (NETIF_F_VLAN_CHALLENGED | \
                                  NETIF_F_LLTX | NETIF_F_NETNS_LOCAL)