ath9k: Fix a DMA latency issue for Intel Pinetrail platforms.

Throughput was severely affected in Intel Pinetrail platforms
because of a DMA problem in C3 state. This patch fixes this
issue.

Signed-off-by: Vivek Natarajan <vnatarajan@atheros.com>
CC: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/init.c b/drivers/net/wireless/ath/ath9k/init.c
index 95b41db..6a0d99e 100644
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -15,6 +15,7 @@
  */
 
 #include <linux/slab.h>
+#include <linux/pm_qos_params.h>
 
 #include "ath9k.h"
 
@@ -179,6 +180,8 @@
 	.write = ath9k_iowrite32,
 };
 
+struct pm_qos_request_list ath9k_pm_qos_req;
+
 /**************************/
 /*     Initialization     */
 /**************************/
@@ -756,6 +759,9 @@
 	ath_init_leds(sc);
 	ath_start_rfkill_poll(sc);
 
+	pm_qos_add_request(&ath9k_pm_qos_req, PM_QOS_CPU_DMA_LATENCY,
+			   PM_QOS_DEFAULT_VALUE);
+
 	return 0;
 
 error_world:
@@ -811,6 +817,8 @@
 
 	ath9k_ps_wakeup(sc);
 
+	pm_qos_remove_request(&ath9k_pm_qos_req);
+
 	wiphy_rfkill_stop_polling(sc->hw->wiphy);
 	ath_deinit_leds(sc);