MFC r344990:
Fix ieee80211_radiotap(9) usage in wireless drivers:

- Alignment issues:
* Add missing __packed attributes + padding across all drivers; in
most places there was an assumption that padding will be always
minimally suitable; in few places - e.g., in urtw(4) / rtwn(4) -
padding was just missing.
* Add __aligned(8) attribute for all Rx radiotap headers since they can
contain 64-bit TSF timestamp; it cannot appear in Tx radiotap headers, so
just drop the attribute here. Refresh ieee80211_radiotap(9) man page
accordingly.

- Since net80211 automatically updates channel frequency / flags in
ieee80211_radiotap_chan_change() drop duplicate setup for these fields
in drivers.

MFC r343474:
Remove 2GHz channel list copies from wireless drivers.

Wrap ieee80211_add_channel_list_2ghz into another function
which supplies default (1-14) channel list to it and drop
its copies from drivers.

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

rtwn: fix Tx processing, add some busdma synchronization.

1) Unload mbuf instead of descriptor in rtwn_tx_done().
2) Add more synchronization for device visible mappings before
touching the memory.
3) Improve watchdog timer logic.

Reported and tested by: mva

Approved by: re (gjb)

urtwn, rtwn, rsu: switch to ieee80211_add_channel_list_2ghz().

- Use device's channel list instead of default one (from
ieee80211_init_channels()); adds 12 - 14 2GHz channels.
- Add ic_getradiocaps() method.

rtwn: replace hardcoded rate indices with their names (similar to r289758).

- Use macros to define rate indices; don't hardcode them in code.
- Add method for 'rate' -> 'rate index' conversion
(and array for the opposite).
- Determine if rate is CCK / OFDM via appropriate macro.

Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D4837

rtwn: fix double free in raw xmit path.

Reported by: mva

net80211 + drivers: hide size of 'bands' array behind a macro.

Auto-replace 'howmany(IEEE80211_MODE_MAX, 8)' with 'IEEE80211_MODE_BYTES'.
No functional changes.

net80211: replace internal LE_READ_*/LE_WRITE_* macro with system
le*dec / le*enc functions.

Replace net80211 specific macros with system-wide bytestream
encoding/decoding functions:
- LE_READ_2 -> le16dec
- LE_READ_4 -> le32dec
- LE_WRITE_2 -> le16enc
- LE_WRITE_4 -> le32enc

+ drop ieee80211_input.h include, where it was included for these
operations only.

Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D6030

rtwn: import r290048.

- Fix scanning from AUTH state.

Tested by: Simone Mario Lombardo <evil.lombo@gmail.com>

PR: 203105
Reviewed by: kevlo
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D4820

rtwn: do not start vap when initialization fails

- Start vap(s) (via ieee80211_start_all()) only when initialization
succeeds; stop the first vap otherwise (via ieee80211_stop());
- Do not try to stop a device multiple times
(move (sc->sc_flags & RTWN_RUNNING) check to urtwn_stop_locked()).

Tested by: kevlo
Reviewed by: kevlo
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D5058

rtwn: use ieee80211_restart_all() for device reset

Tested by: kevlo
Reviewed by: kevlo
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D5057

rtwn: import r290022 (do not filter out control frames in the RX path)

Tested by: kevlo
Reviewed by: kevlo
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D4838

rtwn: fix sequence number assignment (part of r290630)

Reviewed by: kevlo
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D4819

net80211 drivers: fix ieee80211_init_channels() usage

Fix out-of-bounds read (all) / write (11n capable) for drivers
that are using ieee80211_init_channels() to initialize channel list.

Tested with:
* RTL8188EU, STA mode.
* RTL8188CUS, STA mode.
* WUSB54GC, HOSTAP mode.

Approved by: adrian (mentor)
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D4818

[rtwn] bring over initial rtwn driver.

This is a port from openbsd. It's incomplete and unstable, but it's better
than nothing. I have no plans to MFC this until it's complete and stable.

Submitted by: kevlo