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/rt2800usb.c

@@ -673,6 +673,7 @@ static const struct ieee80211_ops rt2800usb_mac80211_ops = {
 	.ampdu_action		= rt2800_ampdu_action,
 	.flush			= rt2x00mac_flush,
 	.get_survey		= rt2800_get_survey,
+	.get_ringparam		= rt2x00mac_get_ringparam,
 };
 
 static const struct rt2800_ops rt2800usb_rt2800_ops = {