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/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 87fabf8..60300b2 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -317,7 +317,7 @@
 	struct ath_buf *bf;
 	int error = 0;
 
-	spin_lock_init(&sc->rx.pcu_lock);
+	spin_lock_init(&sc->sc_pcu_lock);
 	sc->sc_flags &= ~SC_OP_RXFLUSH;
 	spin_lock_init(&sc->rx.rxbuflock);