p54: fix wmm queue settings

This patch fixes a regression (introduced by 453fae72b2f19 "p54: more definitions form lmac_longbow.h and pda.h" )

It turned out that the "ret" variable wasn't initialized and this caused the following warnings/errors to appear:

wmaster1: failed to set TX queue parameters for queue 2
wmaster1: failed to set TX queue parameters for queue 3
wmaster1: failed to set TX queue parameters for queue 1
wmaster1: failed to set TX queue parameters for queue 0

---

diff -Nurp a/drivers/net/wireless/p54/p54common.c b/drivers/net/wireless/p54/p54common.c
@@ -1729,10 +1729,9 @@ static int p54_conf_tx(struct ieee80211_
 	if ((params) && !(queue > 4)) {
 		P54_SET_QUEUE(priv->qos_params[queue], params->aifs,
 			params->cw_min, params->cw_max, params->txop);
+		ret = p54_set_edcf(dev);
 	} else
 		ret = -EINVAL;
-	if (!ret)
-		ret = p54_set_edcf(dev);
 	mutex_unlock(&priv->conf_mutex);
 	return ret;
 }