staging: wfx: update power-save per interface

mac80211 and the device are both able to control power-save per vif.
But, the current code retrieve power-save from wfx_config(). So, it does
not allow to setup power-save independently for each vif. Driver just
has to rely on wfx_bss_info_changed() instead of wfx_config().

wfx_config() has nothing to do anymore, but we keep it since it is
mandatory for mac80211.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200115135338.14374-41-Jerome.Pouiller@silabs.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wfx/sta.c

@@ -826,6 +826,10 @@ void wfx_bss_info_changed(struct ieee80211_hw *hw,
 
 	if (changed & BSS_CHANGED_TXPOWER)
 		hif_set_output_power(wvif, info->txpower);
+
+	if (changed & BSS_CHANGED_PS)
+		wfx_update_pm(wvif);
+
 	mutex_unlock(&wdev->conf_mutex);
 
 	if (do_join)
@@ -1058,18 +1062,7 @@ void wfx_unassign_vif_chanctx(struct ieee80211_hw *hw,
 
 int wfx_config(struct ieee80211_hw *hw, u32 changed)
 {
-	int ret = 0;
-	struct wfx_dev *wdev = hw->priv;
-	struct wfx_vif *wvif;
-
-	if (changed & IEEE80211_CONF_CHANGE_PS) {
-		mutex_lock(&wdev->conf_mutex);
-		wvif = NULL;
-		while ((wvif = wvif_iterate(wdev, wvif)) != NULL)
-			ret = wfx_update_pm(wvif);
-		mutex_unlock(&wdev->conf_mutex);
-	}
-	return ret;
+	return 0;
 }
 
 int wfx_add_interface(struct ieee80211_hw *hw, struct ieee80211_vif *vif)