mac80211: remove drop_unencrypted code

This mechanism was historic, and only ever used by IBSS, which
also doesn't need to have it as it properly manages station's
802.1X PAE state (or, with WEP, always has a key.)

Remove the mechanism to clean up the code.

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

net/mac80211/rx.c

@@ -1912,8 +1912,7 @@ static int ieee80211_drop_unencrypted(struct ieee80211_rx_data *rx, __le16 fc)
 	/* Drop unencrypted frames if key is set. */
 	if (unlikely(!ieee80211_has_protected(fc) &&
 		     !ieee80211_is_nullfunc(fc) &&
-		     ieee80211_is_data(fc) &&
-		     (rx->key || rx->sdata->drop_unencrypted)))
+		     ieee80211_is_data(fc) && rx->key))
 		return -EACCES;
 
 	return 0;