MFC r251481:
  Do not report current link status if driver is not running.
  Reporting link status in driver has a side-effect that makes mii(4)
  check current link status.  mii(4) will call link status change
  callback when it sees link state change.  Normally this wouldn't
  have problems. However, ASF/IPMI firmware can actively access PHY
  regardless of driver's running state such that reporting link
  status for not-running interface can generate meaningless link
  UP/DOWN messages.

  This change also makes dhclient think driver got a valid link
  regardless of link establishment so it will bypass dhclient's
  initial link status check. I think that wouldn't be issue
  though.
MFC r251482,251733:
r251482:
  Correct setting TX random backoff register. This register is
  implemented as a 10 bits linear feedback shift register so only
  lower 10 bits are valid.
  Because this register is used to initialize random backoff interval
  register only when resolved duplex is half-duplex, it wouldn't have
  caused issues in these days.

r251733:
  Fix a typo introduced in r213280. IFM_OPTIONS macro should see
  current media word.