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>
diff --git a/drivers/net/wireless/Kconfig b/drivers/net/wireless/Kconfig
index 8c8edaf..8f5a3f4 100644
--- a/drivers/net/wireless/Kconfig
+++ b/drivers/net/wireless/Kconfig
@@ -17,6 +17,19 @@
 
 if WLAN
 
+config WIRELESS_WDS
+	bool "mac80211-based legacy WDS support" if EXPERT
+	help
+	  This option enables the deprecated WDS support, the newer
+	  mac80211-based 4-addr AP/client support supersedes it with
+	  a much better feature set (HT, VHT, ...)
+
+	  We plan to remove this option and code, so if you find
+	  that you have to enable it, please let us know on the
+	  linux-wireless@vger.kernel.org mailing list, so we can
+	  help you migrate to 4-addr AP/client (or, if it's really
+	  necessary, give up on our plan of removing it).
+
 source "drivers/net/wireless/admtek/Kconfig"
 source "drivers/net/wireless/ath/Kconfig"
 source "drivers/net/wireless/atmel/Kconfig"