xen-blkfront: 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>
[v1: Seperated the drivers/block/cciss_scsi.c out of this patch]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/block/xen-blkfront.c

@@ -157,7 +157,7 @@ static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 	if (end > nr_minors) {
 		unsigned long *bitmap, *old;
 
-		bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
+		bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
 				 GFP_KERNEL);
 		if (bitmap == NULL)
 			return -ENOMEM;