mac80211: TDLS: change BW calculation for WIDER_BW peers

The previous approach simply ignored chandef restrictions when calculating
the appropriate peer BW for a WIDER_BW peer. This could result in a
regulatory violation if both peers indicated 80MHz support, but the
regdomain forbade it.

Change the approach to setting a WIDER_BW peer's BW. Don't exempt it from
the chandef width at first. If during TDLS negotiation the chandef width
is upgraded, update the peer's BW to match.

Fixes: 0fabfaaf

 ("mac80211: upgrade BW of TDLS peers when possible")
Signed-off-by: Arik Nemtsov <arikx.nemtsov@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>