mac80211: Fix BW upgrade for TDLS peers

It is possible that the station is connected to an AP
with bandwidth of 80+80MHz or 160MHz. In such cases
there is no need to perform an upgrade as the maximal
supported bandwidth is 80MHz.

In addition, when upgrading and setting center_freq1
and bandwidth to 80MHz also set center_freq2 to 0.

Fixes: 0fabfaaf

 ("mac80211: upgrade BW of TDLS peers when possible"
Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>