mac80211: wowlan: enable powersave if suspend while ps-polling

If for any reason we're in the middle of PS-polling or awake after
TX due to dynamic powersave while going to suspend, go back to save
power. This might cause a response frame to get lost, but since we
can't really wait for it while going to suspend that's still better
than not enabling powersave which would cause higher power usage
during (and possibly even after) suspend.

Note that this really only affects the very few drivers that use
the powersave implementation in mac80211.

Signed-off-by: Chaitanya T K <chaitanya.mgit@gmail.com>
[rewrite misleading commit log]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>