wireless: deprecate WDS and disable by default

The old WDS 4-addr frame support is very limited, e.g.
 * no encryption is possible on such links
 * it cannot support rate/HT/VHT negotiation
 * management APIs are very restricted

These make the WDS legacy mode useless in practice.

All of these are resolved by the 4-addr AP/client support,
so there's also no reason to improve WDS in the future.

Therefore, add a Kconfig option to disable legacy WDS.
This gives people an "emergency valve" while they migrate
to the better-supported 4-addr AP/client option; we plan
to remove it (and the associated cfg80211/mac80211 code,
which is the ultimate goal) in the future.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/ralink/rt2x00/rt2x00dev.c

@@ -1362,11 +1362,13 @@ int rt2x00lib_probe_dev(struct rt2x00_dev *rt2x00dev)
 	if (rt2x00dev->bcn->limit > 0)
 		rt2x00dev->hw->wiphy->interface_modes |=
 		    BIT(NL80211_IFTYPE_ADHOC) |
-		    BIT(NL80211_IFTYPE_AP) |
 #ifdef CONFIG_MAC80211_MESH
 		    BIT(NL80211_IFTYPE_MESH_POINT) |
 #endif
-		    BIT(NL80211_IFTYPE_WDS);
+#ifdef CONFIG_WIRELESS_WDS
+		    BIT(NL80211_IFTYPE_WDS) |
+#endif
+		    BIT(NL80211_IFTYPE_AP);
 
 	rt2x00dev->hw->wiphy->flags |= WIPHY_FLAG_IBSS_RSN;