rt2x00: rt2800lib: use rt2x00dev->bcn->winfo_size

The beacon data queue is initialized already when
the rt2800_clear_beacon_register() function is called.

Fetch the size of the TXWI descriptor from that
instead of using the winfo_size field of the data
queue descriptor.

The two values are the same, and the use of the
rt2x00dev->bcn->winfo_size value allows us to
get rid of a superfluous pointer dereference.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2800lib.c

@@ -840,7 +840,7 @@ static inline void rt2800_clear_beacon_register(struct rt2x00_dev *rt2x00dev,
 						unsigned int beacon_base)
 {
 	int i;
-	const int txwi_desc_size = rt2x00dev->ops->bcn->winfo_size;
+	const int txwi_desc_size = rt2x00dev->bcn->winfo_size;
 
 	/*
 	 * For the Beacon base registers we only need to clear