iommu/arm-smmu-v3: Avoid open coded arithmetic in memory allocation

kmalloc_array()/kcalloc() should be used to avoid potential overflow when
a multiplication is needed to compute the size of the requested memory.

So turn a devm_kzalloc()+explicit size computation into an equivalent
devm_kcalloc().
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/3f7b9b202c6b6f5edc234ab7af5f208fbf8bc944.1644274051.git.christophe.jaillet@wanadoo.frSigned-off-by: Will Deacon <will@kernel.org>

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2981,10 +2981,10 @@ static int arm_smmu_init_l1_strtab(struct arm_smmu_device *smmu)
 {
 	unsigned int i;
 	struct arm_smmu_strtab_cfg *cfg = &smmu->strtab_cfg;
-	size_t size = sizeof(*cfg->l1_desc) * cfg->num_l1_ents;
 	void *strtab = smmu->strtab_cfg.strtab;
 
-	cfg->l1_desc = devm_kzalloc(smmu->dev, size, GFP_KERNEL);
+	cfg->l1_desc = devm_kcalloc(smmu->dev, cfg->num_l1_ents,
+				    sizeof(*cfg->l1_desc), GFP_KERNEL);
 	if (!cfg->l1_desc)
 		return -ENOMEM;