virtio: fix sparse return void-valued expression warnings

drivers/virtio/virtio_pci.c:148:2: warning: returning void-valued expression
drivers/virtio/virtio_pci.c:155:2: warning: returning void-valued expression

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/virtio/virtio_pci.c

@@ -145,14 +145,14 @@ static void vp_set_status(struct virtio_device *vdev, u8 status)
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	/* We should never be setting status to 0. */
 	BUG_ON(status == 0);
-	return iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+	iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
 }
 
 static void vp_reset(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	/* 0 status means a reset. */
-	return iowrite8(0, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+	iowrite8(0, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
 }
 
 /* the notify function used when creating a virt queue */