MFC r248227:
  Disable TX IP header checksum offloading on RL_HWREV_8168CP. The
  controller generates wrong checksummed frame if the IP packet has
  IP options.
MFC r248456:
  r119712 introduced SIS_TYPE_83816 but it was not actually set in
  driver such that checking against the type was always false.
  To detect NS DP83816, driver should have checked silicon revision
  register for NS controllers. While here, remove SIS_TYPE_83816 to
  not make the similar mistake again.
MFC r248542:
  For RTL8211B or later PHYs, enable crossover detection and
  auto-correction. This change makes re(4) establish a link with
  a system using non-crossover UTP cable.