mac80211: don't validate unchanged AP bandwidth while tracking

mac80211: don't validate unchanged AP bandwidth while tracking

commit 963a1852fbac4f75a2d938fa2e734ef1e6d4c044 upstream.

The MLME code in mac80211 must track whether or not the AP changed
bandwidth, but if there's no change while tracking it shouldn't do
anything, otherwise regulatory updates can make it impossible to
connect to certain APs if the regulatory database doesn't match the
information from the AP. See the precise scenario described in the
code.

This still leaves some possible problems with CSA or if the AP
actually changed bandwidth, but those cases are less common and
won't completely prevent using it.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=70881

Reported-and-tested-by: Nate Carlson <kernel@natecarlson.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>