Vlan EVENT patch

[Jack Vogel]

This is a small patch that Sam came up with for me, it will allow
drivers to know
when a vlan attaches.

It is transparent to any code that doesn't want to change, but this
will allow my
drivers to finally utilize the vlan hardware filter (something Linux has had for
ever but we lacked).

My test group has done some basic testing of this and it is working great.
But we wanted to give any vlan users a chance to see, ask questions, or
whatever before its committed.

Jack