rt2x00: Make rt2800_write_beacon only export to GPL

rt2800_write_beacon is the only function which uses
EXPORT_SYMBOL instead of EXPORT_SYMBOL_GPL. All symbols
in rt2x00 should however use the GPL restricted export.
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2800lib.c

@@ -473,7 +473,7 @@ void rt2800_write_beacon(struct queue_entry *entry, struct txentry_desc *txdesc)
 	dev_kfree_skb_any(entry->skb);
 	entry->skb = NULL;
 }
-EXPORT_SYMBOL(rt2800_write_beacon);
+EXPORT_SYMBOL_GPL(rt2800_write_beacon);
 
 static void inline rt2800_clear_beacon(struct rt2x00_dev *rt2x00dev,
 				       unsigned int beacon_base)