compat: fix system crash on 2.6.35 when flushing work

compat: fix system crash on 2.6.35 when flushing work

Ubuntu 10.10 stock kernel (2.6.35-22-generic) crashes in
compat_flush_scheduled_work(), that is called e.g. when
mac80211 module is unloaded.

The problem was introduced with 80bf8a83
compat: backport system work queues system_wq and system_long_wq

The crash happens in compat_flush_scheduled_work() where both
flush_workqueue() and flush_scheduled_work() are called successively.
Removing one of them resolves the issue.

All compat-wireless tarballs after 2012-03-18 are affected.

Signed-off-by: Zefir Kurtisi <zefir.kurtisi@neratec.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@frijolero.org>