wifi: mac80211: fix RCU usage warning in mesh fast-xmit

In mesh_fast_tx_flush_addr() we already hold the lock, so
don't need additional hashtable RCU protection. Use the
rhashtable_lookup_fast() variant to avoid RCU protection
warnings.

Fixes: d5edb9ae ("wifi: mac80211: mesh fast xmit support")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mesh_pathtbl.c

@@ -648,7 +648,7 @@ void mesh_fast_tx_flush_addr(struct ieee80211_sub_if_data *sdata,
 
 	cache = &sdata->u.mesh.tx_cache;
 	spin_lock_bh(&cache->walk_lock);
-	entry = rhashtable_lookup(&cache->rht, addr, fast_tx_rht_params);
+	entry = rhashtable_lookup_fast(&cache->rht, addr, fast_tx_rht_params);
 	if (entry)
 		mesh_fast_tx_entry_free(cache, entry);
 	spin_unlock_bh(&cache->walk_lock);