mac80211: allow driver to be stateless wrt. SMSP requests

Bail out if no update is made to the SMPS state. This
allows the driver to avoid duplicating the state.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ht.c

@@ -406,6 +406,9 @@ void ieee80211_request_smps(struct ieee80211_vif *vif,
 	if (WARN_ON(smps_mode == IEEE80211_SMPS_OFF))
 		smps_mode = IEEE80211_SMPS_AUTOMATIC;
 
+	if (sdata->u.mgd.driver_smps_mode == smps_mode)
+		return;
+
 	sdata->u.mgd.driver_smps_mode = smps_mode;
 
 	ieee80211_queue_work(&sdata->local->hw,