MFC r221817:

MFC r221817:
  Explicitly clear 1000baseT control register for F1 PHY used in
  AR8132 FastEthernet controller. The PHY has no ability to
  establish a gigabit link. Previously only link parters which
  support down-shifting was able to establish link.
  This change should fix a long standing link establishment issue of
  AR8132.

  PR:	kern/156935

git-svn-id: svn://svn.freebsd.org/base/stable/8@222098 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f