wifi: mac80211: Fix permissions for valid_links debugfs entry

The entry should be a read only one and not a write only one. Fix it.

Fixes: 3d901102 ("wifi: mac80211: implement link switching")
Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230611121219.c75316990411.I1565a7fcba8a37f83efffb0cc6b71c572b896e94@changeid
[remove x16 change since it doesn't work yet]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/debugfs_netdev.c

@@ -720,7 +720,7 @@ static void add_sta_files(struct ieee80211_sub_if_data *sdata)
 	DEBUGFS_ADD_MODE(uapsd_queues, 0600);
 	DEBUGFS_ADD_MODE(uapsd_max_sp_len, 0600);
 	DEBUGFS_ADD_MODE(tdls_wider_bw, 0600);
-	DEBUGFS_ADD_MODE(valid_links, 0200);
+	DEBUGFS_ADD_MODE(valid_links, 0400);
 	DEBUGFS_ADD_MODE(active_links, 0600);
 }