mac80211: add uapsd_queues and max_sp params fields

Add uapsd_queues and max_sp fields to ieee80211_sta.
These fields might be needed by low-level drivers in
order to configure the AP.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>