mac80211: stop toggling IEEE80211_HT_CAP_SUP_WIDTH_20_40

For VHT, many more bandwidth changes are possible. As a first
step, stop toggling the IEEE80211_HT_CAP_SUP_WIDTH_20_40 flag
in the HT capabilities and instead introduce a bandwidth field
indicating the currently usable bandwidth to transmit to the
station. Of course, make all drivers use it.

To achieve this, make ieee80211_ht_cap_ie_to_sta_ht_cap() get
the station as an argument, rather than the new capabilities,
so it can set up the new bandwidth field.

If the station is a VHT station and VHT bandwidth is in use,
also set the bandwidth accordingly.

Doing this allows us to get rid of the supports_40mhz flag as
the HT capabilities now reflect the true capability instead of
the current setting.

While at it, also fix ieee80211_ht_cap_ie_to_sta_ht_cap() to not
ignore HT cap overrides when MCS TX isn't supported (not that it
really happens...)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/mesh_plink.c b/net/mac80211/mesh_plink.c
index a4c7a7e..7765139 100644
--- a/net/mac80211/mesh_plink.c
+++ b/net/mac80211/mesh_plink.c
@@ -373,8 +373,7 @@
 	if (elems->ht_cap_elem &&
 	    sdata->vif.bss_conf.chandef.width != NL80211_CHAN_WIDTH_20_NOHT)
 		ieee80211_ht_cap_ie_to_sta_ht_cap(sdata, sband,
-						  elems->ht_cap_elem,
-						  &sta->sta.ht_cap);
+						  elems->ht_cap_elem, sta);
 	else
 		memset(&sta->sta.ht_cap, 0, sizeof(sta->sta.ht_cap));
 
@@ -383,8 +382,7 @@
 
 		if (!(elems->ht_operation->ht_param &
 		      IEEE80211_HT_PARAM_CHAN_WIDTH_ANY))
-			sta->sta.ht_cap.cap &=
-					    ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
+			sta->sta.bandwidth = IEEE80211_STA_RX_BW_20;
 		ieee80211_ht_oper_to_chandef(sdata->vif.bss_conf.chandef.chan,
 					     elems->ht_operation, &chandef);
 		if (sta->ch_width != chandef.width)