mac80211: align ieee80211_ibss_csa_beacon() with ieee80211_assign_beacon()

The return value of ieee80211_ibss_csa_beacon is not aligned with the
return value of ieee80211_assign_beacon().  For consistency and to be
able to use both functions with similar code, change
ieee80211_ibss_csa_beacon() not to send the bss changed notification
itself, but return what has changed so the caller can send the
notification instead.

Tested by: Simon Wunderlich <sw@simonwunderlich.de>
Acked by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ibss.c

@@ -522,7 +522,7 @@ int ieee80211_ibss_csa_beacon(struct ieee80211_sub_if_data *sdata,
 	if (csa_settings)
 		ieee80211_send_action_csa(sdata, csa_settings);
 
-	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
+	return BSS_CHANGED_BEACON;
  out:
 	return ret;
 }
@@ -563,6 +563,9 @@ int ieee80211_ibss_finish_csa(struct ieee80211_sub_if_data *sdata)
 	if (err < 0)
 		return err;
 
+	if (err)
+		ieee80211_bss_info_change_notify(sdata, err);
+
 	return 0;
 }