iommu/arm-smmu-v3: Use DEFINE_RES_MEM() to simplify code

No functional change.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20210122131448.1167-1-thunder.leizhen@huawei.comSigned-off-by: Will Deacon <will@kernel.org>

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

@@ -3479,11 +3479,7 @@ err_reset_pci_ops: __maybe_unused;
 static void __iomem *arm_smmu_ioremap(struct device *dev, resource_size_t start,
 				      resource_size_t size)
 {
-	struct resource res = {
-		.flags = IORESOURCE_MEM,
-		.start = start,
-		.end = start + size - 1,
-	};
+	struct resource res = DEFINE_RES_MEM(start, size);
 
 	return devm_ioremap_resource(dev, &res);
 }