mac80211: Use a cfg80211_chan_def in ieee80211_hw_conf_chan

Drivers that don't use chanctxes cannot perform VHT association because
they still use a "backward compatibility" pair of {ieee80211_channel,
nl80211_channel_type} in ieee80211_conf and ieee80211_local.

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
[fix kernel-doc]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/drivers/net/wireless/at76c50x-usb.c b/drivers/net/wireless/at76c50x-usb.c
index 5ac5f7a..34c8a33 100644
--- a/drivers/net/wireless/at76c50x-usb.c
+++ b/drivers/net/wireless/at76c50x-usb.c
@@ -1943,12 +1943,12 @@
 	struct at76_priv *priv = hw->priv;
 
 	at76_dbg(DBG_MAC80211, "%s(): channel %d",
-		 __func__, hw->conf.channel->hw_value);
+		 __func__, hw->conf.chandef.chan->hw_value);
 	at76_dbg_dump(DBG_MAC80211, priv->bssid, ETH_ALEN, "bssid:");
 
 	mutex_lock(&priv->mtx);
 
-	priv->channel = hw->conf.channel->hw_value;
+	priv->channel = hw->conf.chandef.chan->hw_value;
 
 	if (is_valid_ether_addr(priv->bssid))
 		at76_join(priv);