p54: return NETDEV_TX_OK in p54_tx and fix sparse warnings

This patch addresses all recent comments from Johannes Berg:

1st: (reference http://marc.info/?l=linux-wireless&m=123124685019631 )
>First off: all those should return NETDEV_TX_OK/BUSY.
>iwl-agn: returns 0 (== NETDEV_TX_OK, but still should be changed)
>[...]
>p54: same (some paths)

2nd:
> due to your PS patch ("p54: power save management"), please run sparse:
> make C=2 CF=-D__CHECK_ENDIAN__ M=...
> +drivers/net/wireless/p54/p54common.c:1753:8: warning: incorrect type in assignment (different base types)
> +drivers/net/wireless/p54/p54common.c:1769:29: warning: incorrect type in assignment (different base types)
The cpu_to_le16 ended up in the wrong line... Sorry!
Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/p54/p54common.c

@@ -1532,7 +1532,7 @@ static int p54_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
 	queue_delayed_work(dev->workqueue, &priv->work,
 			   msecs_to_jiffies(P54_TX_FRAME_LIFETIME));
 
-	return 0;
+	return NETDEV_TX_OK;
 
  err:
 	skb_pull(skb, sizeof(*hdr) + sizeof(*txhdr) + padding);
@@ -1774,7 +1774,7 @@ static int p54_set_ps(struct ieee80211_hw *dev)
 	int i;
 
 	if (dev->conf.flags & IEEE80211_CONF_PS)
-		mode = cpu_to_le16(P54_PSM | P54_PSM_DTIM | P54_PSM_MCBC);
+		mode = P54_PSM | P54_PSM_DTIM | P54_PSM_MCBC;
 	else
 		mode = P54_PSM_CAM;
 
@@ -1790,7 +1790,7 @@ static int p54_set_ps(struct ieee80211_hw *dev)
 	for (i = 0; i < ARRAY_SIZE(psm->intervals); i++) {
 		psm->intervals[i].interval =
 			cpu_to_le16(dev->conf.listen_interval);
-		psm->intervals[i].periods = 1;
+		psm->intervals[i].periods = cpu_to_le16(1);
 	}
 
 	psm->beacon_rssi_skip_max = 60;