[net80211] RX parameter shuffle in net80211 in preparation for 4x4 NICs and 160MHz channels.

• Migrate the rx_params stuff out from ieee80211_freebsd.h where it doesn't belong - this isn't freebsd specific anymore.

• Don't use a hard-coded number of chains in the ioctl header; now we can shuffle MAX_CHAINS around so it can be used in the right spot.

• Extend the signal/noisefloor levels in the mimo stats struct to userland to include the signal and noisefloor levels for each 20MHz slice of a 160MHz channel.

• Bump the number of EVM pilots in preparation for 4x4 and 160MHz channels.

Tested:

• ath(4), STA mode
• iwn(4), STA mode
• local ath10k port, STA mode

TODO:

• 11ax chips will come with 5GHz 8x8 hardware for lots of MU-MIMO - I'll re-bump it at that point.

Note:

• This breaks the driver and ifconfig ABI; please recompile the kernel, ifconfig and wpa_supplicant/hostapd.