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: NJohannes Berg <johannes.berg@intel.com>

Like with HT, make things a bit simpler in future patches by
passing the station to ieee80211_vht_cap_ie_to_sta_vht_cap()
instead of the vht_cap pointer. Also disable VHT here if HT
isn't supported.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>

Save the AP's VHT capabilities (in managed
mode) and make them available to the driver
in the station information.

Unlike HT capabilities, they aren't restricted
to the common capabilities, so drivers must be
aware of their own capabilities.
Signed-off-by: NMahesh Palivela <maheshp@posedge.com>
[fix endian conversion bug ...]
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>