mac80211: allow the driver not to pass the tid to ieee80211_sta_uapsd_trigger

iwlwifi will check internally that the tid maps to an AC
that is trigger enabled, but can't know what tid exactly.
Allow the driver to pass a generic tid and make mac80211
assume that a trigger frame was received.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index e50c9e0..f3dbada 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -4087,6 +4087,10 @@ void ieee80211_sta_pspoll(struct ieee80211_sta *sta);
  * This must be used in conjunction with ieee80211_sta_ps_transition()
  * and possibly ieee80211_sta_pspoll(); calls to all three must be
  * serialized.
+ * %IEEE80211_NUM_TIDS can be passed as the tid if the tid is unknown.
+ * In this case, mac80211 will not check that this tid maps to an AC
+ * that is trigger enabled and assume that the caller did the proper
+ * checks.
  */
 void ieee80211_sta_uapsd_trigger(struct ieee80211_sta *sta, u8 tid);