Wi-Fi ac support

[Adrian Chadd]

Hi!

There's no active 11ac plans or work going on. We're bringing up the
intel 7260 driver chipset family on FreeBSD-HEAD so there'll be at
least one 11ac chipset supported. That'll make it easier for me or
whoever else wishes to bring up 11ac support.

Luckily, 11ac support in net80211 isn't that complicated - the most
tricky bit is bringing up the 11ac channel list and IE parameter
negotiation. The rest of it looks mostly like 11n.



-adrian