MFC r318001:

[iwm] include opt_iwm.h and opt_wlan.h consistently in all files.

MFC r318219:

[iwm] Properly implement iwm_wme_update callback function.

* Inspired by iwn(4) and Linux iwlwifi.

* Read wme parameters into a buffer within struct iwm_vap in
iwm_wme_update().

* If we aren't associated yet, the new settings will soon be sent
by iwm_mvm_mac_ctxt_changed() during association.

* If we are already associated, explicitly call iwm_mvm_mac_ctxt_changed()
from iwm_wme_update() to send the new settings to the firmware.

* Change iwm_mvm_ac_to_tx_fifo mapping, to fit the freebsd net80211
WME stream class numbering, instead of Linux's enum ieee80211_ac_numbers.

MFC r318214:

[iwm] Sanity check channel for IEEE80211_CHAN_ANYC in if_iwm_mac_ctxt.c.

* This avoids panicing in some broken vap state handling cases.

MFC r315926:

[iwm] Add the BSS's basic rates to iwm's LQ command, not all the rates.

Makes the firmware use appropriate Tx rates for ACKs.

MFC r313307:

[iwm] TODO for QOS support.

MFC r303322,303326,303327,303345,303413,303416,303418,303557

Update iwm(4) and iwmfw(4) to current in order to stabilize and improve
functionality.

Approved by: re (gjb)