at76c50x-usb: add link to the TODO list

It's easier to have the TODO list in wiki, so add a link to the list.
Signed-off-by: Kalle Valo <kalle.valo@iki.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/at76c50x-usb.c

@@ -18,14 +18,10 @@
  *
  * Some iw_handler code was taken from airo.c, (C) 1999 Benjamin Reed
  *
- * TODO for the mac80211 port:
- * o adhoc support
- * o RTS/CTS support
- * o Power Save Mode support
- * o support for short/long preambles
- * o export variables through debugfs/sysfs
- * o remove hex2str
- * o remove mac2str
+ * TODO list is at the wiki:
+ *
+ * http://wireless.kernel.org/en/users/Drivers/at76c50x-usb#TODO
+ *
  */
 
 #include <linux/init.h>