mac80211: align ieee80211_mesh_csa_beacon() with ieee80211_assign_beacon()

The return value of ieee80211_mesh_csa_beacon is not aligned with the
return value of ieee80211_assign_beacon() and
ieee80211_ibss_csa_beacon().  For consistency and to be able to use
both functions with similar code, change ieee80211_mesh_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/mesh.c

@@ -1104,12 +1104,10 @@ int ieee80211_mesh_csa_beacon(struct ieee80211_sub_if_data *sdata,
 		return ret;
 	}
 
-	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
-
 	if (csa_action)
 		ieee80211_send_action_csa(sdata, csa_settings);
 
-	return 0;
+	return BSS_CHANGED_BEACON;
 }
 
 static int mesh_fwd_csa_frame(struct ieee80211_sub_if_data *sdata,