wiphy: Fix memory leak

Whenever we find an existing BSS, we should free the old object since it
is being removed from the old_bss_list via l_queue_remove_if

src/wiphy.c

@@ -641,6 +641,8 @@ static void parse_bss(struct netdev *netdev, struct l_genl_attr *attr)
 						bss_address_to_string(bss));
 		if (network)
 			network->bss = bss;
+
+		bss_free(old_bss);
 	}
 
 	l_queue_push_head(netdev->bss_list, bss);