ath9k: rename rxflushlock to pcu_lock

The real way to lock RX is to contend on the PCU
and reset, this will be fixed in the next patch but for
now just do the renames so that the next patch which changes
the locking order is crystal clear.

This is part of a series that will help resolve the bug:

https://bugzilla.kernel.org/show_bug.cgi?id=14624

For more details about this issue refer to:

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

Cc: stable@kernel.org
Cc: Ben Greear <greearb@candelatech.com>
Cc: Kyungwan Nam <kyungwan.nam@atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Tested-by: Ben Greear <greearb@candelatech.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 973c919..9b8e7e3 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -310,7 +310,7 @@
 	u8 rxotherant;
 	u32 *rxlink;
 	unsigned int rxfilter;
-	spinlock_t rxflushlock;
+	spinlock_t pcu_lock;
 	spinlock_t rxbuflock;
 	struct list_head rxbuf;
 	struct ath_descdma rxdma;