net: wireless: move regulatory timeout work to power efficient workqueue

For better use of CPU idle time, allow the scheduler to select the CPU
on which the timeout work of regulatory settings would be executed.
This extends CPU idle residency time and saves power.

This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected.

Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Shaibal Dutta <shaibal.dutta@broadcom.com>
[zoran.markovic@linaro.org: Rebased to latest kernel. Added commit message.]
Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/reg.c

@@ -1701,7 +1701,8 @@ static void reg_process_hint(struct regulatory_request *reg_request)
 		if (treatment == REG_REQ_OK ||
 		    treatment == REG_REQ_ALREADY_SET)
 			return;
-		schedule_delayed_work(&reg_timeout, msecs_to_jiffies(3142));
+		queue_delayed_work(system_power_efficient_wq,
+				   &reg_timeout, msecs_to_jiffies(3142));
 		return;
 	case NL80211_REGDOM_SET_BY_DRIVER:
 		if (!wiphy)
@@ -2301,7 +2302,8 @@ static int reg_set_rd_driver(const struct ieee80211_regdomain *rd,
 
 	request_wiphy = wiphy_idx_to_wiphy(driver_request->wiphy_idx);
 	if (!request_wiphy) {
-		schedule_delayed_work(&reg_timeout, 0);
+		queue_delayed_work(system_power_efficient_wq,
+				   &reg_timeout, 0);
 		return -ENODEV;
 	}
 
@@ -2361,7 +2363,8 @@ static int reg_set_rd_country_ie(const struct ieee80211_regdomain *rd,
 
 	request_wiphy = wiphy_idx_to_wiphy(country_ie_request->wiphy_idx);
 	if (!request_wiphy) {
-		schedule_delayed_work(&reg_timeout, 0);
+		queue_delayed_work(system_power_efficient_wq,
+				   &reg_timeout, 0);
 		return -ENODEV;
 	}