mac80211_hwsim: don't use WQ_MEM_RECLAIM

We're obviously not part of a memory reclaim path, so don't set the flag.

This also causes a warning in check_flush_dependency() since we end up
in a code path that flushes a non-reclaim workqueue, and we shouldn't do
that if we were really part of reclaim.

Reported-by:  <syzbot+41cdaf4232c50e658934@syzkaller.appspotmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>