iwlwifi: set default aggregation frame count limit to 31

Multiple MPDUs can be aggregated, transmitted, and finally acknowledged
together using a single BA frame. Block ACK (BA) contains
bitmap size of 64*16 bits so the maximum frame count is 64.
The default value of aggregation frame count suggested by uCode is 31 to
achieve best performance.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-agn-rs.c

@@ -2800,7 +2800,7 @@ static void rs_fill_link_cmd(struct iwl_priv *priv,
 		repeat_rate--;
 	}
 
-	lq_cmd->agg_params.agg_frame_cnt_limit = LINK_QUAL_AGG_FRAME_LIMIT_MAX;
+	lq_cmd->agg_params.agg_frame_cnt_limit = LINK_QUAL_AGG_FRAME_LIMIT_DEF;
 	lq_cmd->agg_params.agg_dis_start_th = LINK_QUAL_AGG_DISABLE_START_DEF;
 	lq_cmd->agg_params.agg_time_limit =
 		cpu_to_le16(LINK_QUAL_AGG_TIME_LIMIT_DEF);