MFC r206364:

MFC r206364:
  Partial revert r204545.
  Just relying on status LE ownership of status block seems to cause
  poor performance. Always read current status index register first
  and then check status ownership as we had before. Accessing status
  index register seems to trigger immediate status update if
  controller have pending status updates.

  Reported by:	Andre Albsmeier <Andre.Albsmeier <> siemens dot com>
  Tested by:	Andre Albsmeier <Andre.Albsmeier <> siemens dot com>

git-svn-id: svn://svn.freebsd.org/base/stable/8@206575 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f