cfg80211: validate nl80211 station handling better

The nl80211 station handling code is a bit messy
and doesn't do a lot of validation. It seems like
this could be an issue for drivers that don't use
mac80211 to validate everything.

As cfg80211 doesn't keep station state, move the
validation of allowing supported_rates to change
for TDLS only in station mode to mac80211.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index a187606..f795cb7 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -1536,7 +1536,11 @@
  * @NL80211_STA_FLAG_WME: station is WME/QoS capable
  * @NL80211_STA_FLAG_MFP: station uses management frame protection
  * @NL80211_STA_FLAG_AUTHENTICATED: station is authenticated
- * @NL80211_STA_FLAG_TDLS_PEER: station is a TDLS peer
+ * @NL80211_STA_FLAG_TDLS_PEER: station is a TDLS peer -- this flag should
+ *	only be used in managed mode (even in the flags mask). Note that the
+ *	flag can't be changed, it is only valid while adding a station, and
+ *	attempts to change it will silently be ignored (rather than rejected
+ *	as errors.)
  * @NL80211_STA_FLAG_MAX: highest station flag number currently defined
  * @__NL80211_STA_FLAG_AFTER_LAST: internal use
  */