[net80211] begin fleshing out per-VAP WME configurations.

As part of (eventual) p2p/tdls/multi-STA support, a lot of global configuration
parameters (WME, ERP (slot, preamble), channel width, HT protmode, etc are the
biggest offenders) should be per-VAP.

For multi-BSS VAP operation they may be linked, but for p2p/TDLS
operation that can be off-channel they can definitely be different
(think: 2GHz STA, 5GHz p2p.)

The global configuration view of these is mostly a "configure the current
non-smart-firmware NIC" view. This should be split up into per-VAP state,
then a global non-smart-firmware-NIC management layer to handle channel
changes and such in software.

This is step one in a loooong road for this. It should be a big non-functional
change for everyone.

• create a per-VAP WME update call.
• call it if its set, and call the global callback if it isn't

This still uses global WME state - it's just preparation for a future change
which will make the WME state per-VAP and fall through to a shared WME
configuration for hostap operation.

Note: this requires a full kernel recompile; the internal net80211 ABI has changed.

Reviewed by: avos
Differential Revision: https://reviews.freebsd.org/D9986