Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

net80211: fix more compiler warnings.

ieee80211.c:
add_chanlist(): 'error' variable will be uninitialized if
no channels were passed; return '0' instead.
ieee80211_action.c:
ieee80211_send_action_register(): drop 'break' after 'return'.
ieee80211_crypto_none.c:
none_encap(): 'keyid' is not used in non-debug builds; hide it
behind IEEE80211_DEBUG ifdef.
ieee80211_freebsd.c:
Staticize global 'ieee80211_debug' variable (used only in this
file).
ieee80211_hostap.c:
Fix a comment (associatio -> association).
ieee80211_ht.c:
ieee80211_setup_htrates(): initialize 'maxunequalmcs' to 0 to mute
compiler warning.
ieee80211_hwmp.c:
hwmp_recv_preq(): copy 'prep' between conditional blocks to fix
-Wshadow warning.
ieee80211_mesh.c:
mesh_newstate(): remove duplicate 'ni' definition.
mesh_recv_group_data(): fix -Wempty-body warning in non-debug
builds.
ieee80211_phy.c:
ieee80211_compute_duration(): remove 'break' after panic() call.
ieee80211_scan_sta.c:
Hide some TDMA-specific macros under IEEE80211_SUPPORT_TDMA ifdef
adhoc_pick_bss(): remove 'ic' pointer redefinition.
ieee80211_sta.c:
sta_beacon_miss(): remove 'ic' pointer redefinition.
ieee80211_superg.c:
superg_ioctl_set80211(): drop unreachable return.

Tested with clang 3.8.0, gcc 4.6.4 and gcc 5.3.0.

net80211: drop some unused variables / local macros

Most of them left after some commits (r178354, r191544, r287197 etc.);
some were never used.

Found by: Clang Static Analyzer

[net80211] rename 11n rate macros into a useful spot

* begin moving the 11n macros out of ieee80211_phy.c and
into a header so they can be used elsewhere.

* rename some of them into the IEEE80211_* namespace.

* convert HT_RC_2_MCS() to work with three-stream rates.

Provide includes that are needed in these files, and before were read
in implicitly via if.h -> if_var.h pollution.

Sponsored by: Netflix
Sponsored by: Nginx, Inc.

Replace the homegrown implementation of nitems() with calls to nitems()
(param.h).

Operating systems that don't have nitems() can easily define it on their own
net80211 OS-specific header file.

Discussed with: adrian

Implement basic 802.11n awareness in the PHY and AMRR rate control code.

* Add 802.11n 2ghz and 5ghz tables, including legacy rates and up to
MCS23 rates (3x3.)

* Populate the rate code -> rate index lookup table with MCS _and_
normal rates, but _not_ the basic rate flag. Since the basic rate flag
is the same as the MCS flag, we can only use one.

* Introduce some accessor inlines that do PLCP and rate table lookup/access
and enforce that it doesn't set the basic rate bit. They're not
designed for MCS rates, so it will panic.

* Start converting drivers that use the rate table stuff to use the
accessor inlines and strip the basic flag.

* Teach AMRR about basic 11n - it's still as crap for MCS as it is
being used by iwn, so it's not a step _backwardS_.

* Convert iwn over to accept 11n MCS rates rather than 'translate' legacy
to MCS rates. It doesn't use a lookup table any longer; instead it's a
function which takes the current node (for HT parameters) and the
rate code, and returns the hardware PLCP code to use.

Tested:

* ath - it's a no-op, and it works that way
* iwn - both 11n and non-11n

use 1/2 and 1/4 rate phy types to simplify txtime calculation

use c99 syntax for initializers; this silences
warnings with picky compiler settings

Update PLCP<->rate mapping support:
o correct mapping of CCK rates to PLCP; was using nonstandard Ralink
values which just happened to also be used by Zydas (so went unnoticed)
o change ieee80211_plcp2rate api to take a phy type instead of a flag
that indicates ofdm/!ofdm
o update drivers to match (restore per-driver code to map rate->PLCP)

Reviewed by: sephe, weongyo, thompsa

Multi-bss (aka vap) support for 802.11 devices.

Note this includes changes to all drivers and moves some device firmware
loading to use firmware(9) and a separate module (e.g. ral). Also there
no longer are separate wlan_scan* modules; this functionality is now
bundled into the wlan module.

Supported by: Hobnob and Marvell
Reviewed by: many
Obtained from: Atheros (some bits)