rt2x00: Fix tx parameter initialization

Check if the aifs, cw_min and cw_max are above 0
when determining if the default should be used.
Tor aifs a negative number is used to determine
if the default should be used or not.
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2x00mac.c

@@ -396,17 +396,17 @@ int rt2x00mac_conf_tx(struct ieee80211_hw *hw, int queue_idx,
 	 * The passed variables are stored as real value ((2^n)-1).
 	 * Ralink registers require to know the bit number 'n'.
 	 */
-	if (params->cw_min)
+	if (params->cw_min > 0)
 		queue->cw_min = fls(params->cw_min);
 	else
 		queue->cw_min = 5; /* cw_min: 2^5 = 32. */
 
-	if (params->cw_max)
+	if (params->cw_max > 0)
 		queue->cw_max = fls(params->cw_max);
 	else
 		queue->cw_max = 10; /* cw_min: 2^10 = 1024. */
 
-	if (params->aifs)
+	if (params->aifs >= 0)
 		queue->aifs = params->aifs;
 	else
 		queue->aifs = 2;