iwlagn: change the logging level for aggregation enable check

Aggregation will not enable if the traffic is lower than the threshold,
this is not an error condition, so change the logging level.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
index 592b0cf..85e0828 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
@@ -426,7 +426,7 @@
 			ieee80211_stop_tx_ba_session(sta, tid);
 		}
 	} else {
-		IWL_ERR(priv, "Aggregation not enabled for tid %d "
+		IWL_DEBUG_HT(priv, "Aggregation not enabled for tid %d "
 			"because load = %u\n", tid, load);
 	}
 	return ret;