vr(4) resets when entering/leaving promiscuous mode

[Dave Huang <khym%azeotrope.org@localhost>]

As noted in PR kern/29126, a number of Ethernet drivers would reset
the adapter when modifying the MAC filter, causing the link to go down
temporarily. Many have been fixed, but according to the PR, fxp and vr
were still unfixed as of Aug 2009.

I haven't noticed the problem with fxp, so perhaps it's been fixed
since then, but I do still see it with vr. Is this something someone
can easily make a patch for, or should I attempt to come up with one
myself? :)