em0, VLAN and bpf(?) trouble w/RELENG_5

[astesin at ukrtelecom.net]

> A weird thing about that.. I compiled it in, "device vlan" ..but the 
> modules is loaded. And when I boot, I see it trying to load 
> the kernel module again after its loaded.

Someday with 4.* I've got the very same behaviour but I didn't bother, just
used a module since then, as that was told to be an "official" way to go.