MFC r211089:

MFC r211089:
  It seems some old Sundace(now IC Plus Corp.) controllers do not
  like memory mapped register access. Typical problem from the issue
  was MII access returned unreliable values. I'm not sure this comes
  from lack of register flushing in MII access after accessing
  STE_PHYCTL register though.
  To address the issue, read hints data that controls which type of
  memory mapping should be used in driver. ste(4) still prefers
  memory mapping to io mapping but honor hints entered by user except
  for controllers that have problems with memory mapping.
  The hint to use iomapping could be given by adding the following
  line to /boot/device.hints file.

  hint.ste.0.prefer_iomap="1"

  PR:	kern/149285

git-svn-id: svn://svn.freebsd.org/base/stable/8@211357 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f