ethtool: update mapping of features to legacy ioctl requests

Legacy ioctl request like ETHTOOL_GTXCSUM are still used by ethtool utility
to get values of legacy flags (which rather work as feature groups). These
are calculated from values of actual features and request to set them is
implemented as an attempt to set all features mapping to them but there are
two inconsistencies:

- tx-checksum-fcoe-crc is shown under tx-checksumming but NETIF_F_FCOE_CRC
  is not included in ETHTOOL_GTXCSUM/ETHTOOL_STXCSUM
- tx-scatter-gather-fraglist is shown under scatter-gather but
  NETIF_F_FRAGLIST is not included in ETHTOOL_GSG/ETHTOOL_SSG

As the mapping in ethtool output is more correct from logical point of
view, fix ethtool_get_feature_mask() to match it.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>