rt2x00: Remove last usage of beacon_int from ieee80211_config

This removes the last usage of beacon_int inside the iee80211_config
structure from rt2x00. The attempt is a bit hackish, and subject to
change in the future when the entire rt2x00_dev structure is
cleaned up and restructured.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2500usb.c b/drivers/net/wireless/rt2x00/rt2500usb.c
index 69f966f..66daf68 100644
--- a/drivers/net/wireless/rt2x00/rt2500usb.c
+++ b/drivers/net/wireless/rt2x00/rt2500usb.c
@@ -647,7 +647,7 @@
 	if (state == STATE_SLEEP) {
 		rt2500usb_register_read(rt2x00dev, MAC_CSR18, &reg);
 		rt2x00_set_field16(&reg, MAC_CSR18_DELAY_AFTER_BEACON,
-				   libconf->conf->beacon_int - 20);
+				   rt2x00dev->beacon_int - 20);
 		rt2x00_set_field16(&reg, MAC_CSR18_BEACONS_BEFORE_WAKEUP,
 				   libconf->conf->listen_interval - 1);