mtd: physmap.c: use resource_size()

index 426461a..829aa4b 100644
@@ -106,12 +106,12 @@ static int physmap_flash_probe(struct platform_device *dev)
 
 	for (i = 0; i < dev->num_resources; i++) {
 		printk(KERN_NOTICE "physmap platform flash device: %.8llx at %.8llx\n",
-		       (unsigned long long)(dev->resource[i].end - dev->resource[i].start + 1),
+		       (unsigned long long)resource_size(&dev->resource[i]),
 		       (unsigned long long)dev->resource[i].start);
 
 		if (!devm_request_mem_region(&dev->dev,
 			dev->resource[i].start,
-			dev->resource[i].end - dev->resource[i].start + 1,
+			resource_size(&dev->resource[i]),
 			dev_name(&dev->dev))) {
 			dev_err(&dev->dev, "Could not reserve memory region\n");
 			err = -ENOMEM;

@@ -120,7 +120,7 @@ static int physmap_flash_probe(struct platform_device *dev)
 
 		info->map[i].name = dev_name(&dev->dev);
 		info->map[i].phys = dev->resource[i].start;
-		info->map[i].size = dev->resource[i].end - dev->resource[i].start + 1;
+		info->map[i].size = resource_size(&dev->resource[i]);
 		info->map[i].bankwidth = physmap_data->width;
 		info->map[i].set_vpp = physmap_data->set_vpp;
 		info->map[i].pfow_base = physmap_data->pfow_base;