rt2x00: Use kcalloc instead of kzalloc to allocate array

The advantage of kcalloc is, that will prevent integer overflows which could
result from the multiplication of number of elements and size and it is also
a bit nicer to read.

The semantic patch that makes this change is available
in https://lkml.org/lkml/2011/11/25/107

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2x00dev.c

@@ -831,11 +831,11 @@ static int rt2x00lib_probe_hw_modes(struct rt2x00_dev *rt2x00dev,
 	if (spec->supported_rates & SUPPORT_RATE_OFDM)
 		num_rates += 8;
 
-	channels = kzalloc(sizeof(*channels) * spec->num_channels, GFP_KERNEL);
+	channels = kcalloc(spec->num_channels, sizeof(*channels), GFP_KERNEL);
 	if (!channels)
 		return -ENOMEM;
 
-	rates = kzalloc(sizeof(*rates) * num_rates, GFP_KERNEL);
+	rates = kcalloc(num_rates, sizeof(*rates), GFP_KERNEL);
 	if (!rates)
 		goto exit_free_channels;