mac80211: always synchronize_net() during station removal

mac80211: always synchronize_net() during station removal

commit 27a737ff7cb062fb9cbceba9b44d60aa74862bfa upstream.

If there are keys left during station removal, then a
synchronize_net() will be done (for each key, I have a
patch to address this for 3.10), otherwise it won't be
done at all which causes issues because the station
could be used for TX while it's being removed from the
driver -- that might confuse the driver.

Fix this by always doing synchronize_net() if no key
was present any more.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>