ath9k: spin_lock_bh is not required within tasklet context.

Disabling BH is not required while running from a tasklet context
and so replace spin_lock_bh with just spin_lock.
Signed-off-by: Senthil Balasubramanian <senthilkumar@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/main.c

@@ -599,7 +599,7 @@ void ath9k_tasklet(unsigned long data)
 		return;
 	}
 
-	spin_lock_bh(&sc->sc_pcu_lock);
+	spin_lock(&sc->sc_pcu_lock);
 
 	if (!ath9k_hw_check_alive(ah))
 		ieee80211_queue_work(sc->hw, &sc->hw_check_work);
@@ -643,7 +643,7 @@ void ath9k_tasklet(unsigned long data)
 	/* re-enable hardware interrupt */
 	ath9k_hw_enable_interrupts(ah);
 
-	spin_unlock_bh(&sc->sc_pcu_lock);
+	spin_unlock(&sc->sc_pcu_lock);
 	ath9k_ps_restore(sc);
 }