wl1251: Implement delayed entry into ELP mode

Implement (slightly) delayed entry into ELP. This will cure several
problems:
  - It works around a firmware race condition if ELP is entered too fast
    after commands (resulting in ELP timeout -traces)
  - It will reduce the number of sleep-wake cycles between already
    scheduled events such as interrupts and tx, hence improving
    performance (less delay in switching between RX and TX)

Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Vidhya Govindan <vidhya.govindan@nokia.com>
Signed-off-by: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/wl12xx/wl1251_main.c b/drivers/net/wireless/wl12xx/wl1251_main.c
index 900e6e2..b5e3bdb 100644
--- a/drivers/net/wireless/wl12xx/wl1251_main.c
+++ b/drivers/net/wireless/wl12xx/wl1251_main.c
@@ -1367,6 +1367,7 @@
 	skb_queue_head_init(&wl->tx_queue);
 
 	INIT_WORK(&wl->filter_work, wl1251_filter_work);
+	INIT_DELAYED_WORK(&wl->elp_work, wl1251_elp_work);
 	wl->channel = WL1251_DEFAULT_CHANNEL;
 	wl->scanning = false;
 	wl->default_key = 0;