virtio-mmio: convert to devm_platform_ioremap_resource

Use devm_platform_ioremap_resource() to simplify code, which
contains platform_get_resource, devm_request_mem_region and
devm_ioremap.
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio_mmio.c

@@ -531,18 +531,9 @@ static void virtio_mmio_release_dev(struct device *_d)
 static int virtio_mmio_probe(struct platform_device *pdev)
 {
 	struct virtio_mmio_device *vm_dev;
-	struct resource *mem;
 	unsigned long magic;
 	int rc;
 
-	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!mem)
-		return -EINVAL;
-
-	if (!devm_request_mem_region(&pdev->dev, mem->start,
-			resource_size(mem), pdev->name))
-		return -EBUSY;
-
 	vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
 	if (!vm_dev)
 		return -ENOMEM;
@@ -554,9 +545,9 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	INIT_LIST_HEAD(&vm_dev->virtqueues);
 	spin_lock_init(&vm_dev->lock);
 
-	vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
-	if (vm_dev->base == NULL)
-		return -EFAULT;
+	vm_dev->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(vm_dev->base))
+		return PTR_ERR(vm_dev->base);
 
 	/* Check magic value */
 	magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);