ath9k: move the PCU lock to the sc structure

The PCU lock should be used to contend TX DMA as well,
this will be done next.

This is part of a series of patches which fix stopping
TX DMA completley when requested on the driver.
For more details about this issue refer to this thread:

http://marc.info/?l=linux-wireless&m=128629803703756&w=2

Tested-by:  Ben Greear <greearb@candelatech.com>
Cc: Kyungwan Nam <kyungwan.nam@atheros.com>
Cc: stable@kernel.org
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index cb9194a..61d4507 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -309,7 +309,6 @@
 	u8 rxotherant;
 	u32 *rxlink;
 	unsigned int rxfilter;
-	spinlock_t pcu_lock;
 	spinlock_t rxbuflock;
 	struct list_head rxbuf;
 	struct ath_descdma rxdma;
@@ -601,6 +600,7 @@
 	int irq;
 	spinlock_t sc_serial_rw;
 	spinlock_t sc_pm_lock;
+	spinlock_t sc_pcu_lock;
 	struct mutex mutex;
 	struct work_struct paprd_work;
 	struct work_struct hw_check_work;