ipw2x00: Write outside array bounds

> channel_index loops up to IPW_SCAN_CHANNELS, but is used after being
> incremented. This might be able to access 1 past the end of the array

Reported-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ipw2x00/ipw2200.c

@@ -6226,7 +6226,7 @@ static void ipw_add_scan_channels(struct ipw_priv *priv,
 			};
 
 			u8 channel;
-			while (channel_index < IPW_SCAN_CHANNELS) {
+			while (channel_index < IPW_SCAN_CHANNELS - 1) {
 				channel =
 				    priv->speed_scan[priv->speed_scan_pos];
 				if (channel == 0) {