rt2x00: Implement get_ringparam callback function

With the get_ringparam callback function we can export ring parameters
to ethtool through the mac80211 interface.

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/rt2500usb.c

@@ -1823,6 +1823,7 @@ static const struct ieee80211_ops rt2500usb_mac80211_ops = {
 	.conf_tx		= rt2x00mac_conf_tx,
 	.rfkill_poll		= rt2x00mac_rfkill_poll,
 	.flush			= rt2x00mac_flush,
+	.get_ringparam		= rt2x00mac_get_ringparam,
 };
 
 static const struct rt2x00lib_ops rt2500usb_rt2x00_ops = {