MFC r218710:

MFC r218710:
  Fix a regression introduced in r215906. The change made in r215906
  caused link re-negotiation whenever application joins or leaves a
  multicast group.  If driver is running, it would have established a
  link so there is no need to start re-negotiation. The re-negotiation
  broke established link which in turn stopped multicast application
  working while re-negotiation is in progress.

  PR:	kern/154667

git-svn-id: svn://svn.freebsd.org/base/stable/8@218962 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f