mac80211: revert on-channel work optimisations

commit e76aadc5 upstream.

Backport note:
This patch it's a full revert of commit b23b025f "mac80211: Optimize
scans on current operating channel.". On upstrem revert e76aadc5 we
keep some bits from that commit, which are needed for upstream version
of mac80211.

The on-channel work optimisations have caused a
number of issues, and the code is unfortunately
very complex and almost impossible to follow.
Instead of attempting to put in more workarounds
let's just remove those optimisations, we can
work on them again later, after we change the
whole auth/assoc design.

This should fix rate_control_send_low() warnings,
see RH bug 731365.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>