station: print which BSS is being connected to

For multi-bss networks its nice to know which BSS is being connected
to. The ranking can hint at it, but blacklisting or network capabilities
could effect which network is actually chosen. An explicit debug print
makes debugging much easier.

src/station.c

@@ -2423,6 +2423,8 @@ int __station_connect_network(struct station *station, struct network *network,
 		return r;
 	}
 
+	l_debug("connecting to BSS "MAC, MAC_STR(bss->addr));
+
 	station->connected_bss = bss;
 	station->connected_network = network;