MFC r223405:

MFC r223405:
  Remove link state change callback handler.  There is no need to
  register both status change and link state change callbacks.
  Implement checking valid link in state change callback and poll
  active link state in vr_tick().  This allows immediate detection of
  lost link as well as protecting driver from frequent link flips during
  link renegotiation.  taskq implementation was removed because driver
  now needs to poll link state in vr_tick().
  While I'm here do not report current link state if interface is not
  running.

  Tested by:	n_hibma

git-svn-id: svn://svn.freebsd.org/base/stable/8@223681 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f