hwrng: n2 - Use devm_kcalloc() in n2rng_probe()

* A multiplication for the size determination of a memory allocation
  indicated that an array data structure should be processed.
  Thus use the corresponding function "devm_kcalloc".

* Replace the specification of a data structure by a pointer dereference
  to make the corresponding size determination a bit safer according to
  the Linux coding style convention.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/n2-drv.c

@@ -748,9 +748,7 @@ static int n2rng_probe(struct platform_device *op)
 
 	dev_info(&op->dev, "Registered RNG HVAPI major %lu minor %lu\n",
 		 np->hvapi_major, np->hvapi_minor);
-
-	np->units = devm_kzalloc(&op->dev,
-				 sizeof(struct n2rng_unit) * np->num_units,
+	np->units = devm_kcalloc(&op->dev, np->num_units, sizeof(*np->units),
 				 GFP_KERNEL);
 	err = -ENOMEM;
 	if (!np->units)