virtio_console: drop unused config fields

struct ports_device includes a config field including the whole
virtio_console_config, but only max_nr_ports in there is ever updated or
used. The rest is unused and in fact does not even mirror the
device config. Drop everything except max_nr_ports,
saving some memory.

Signed-off-by: Michael S. Tsirkin <[e-mail]>
Reviewed-by: Jason Wang <[e-mail]>

drivers/char/virtio_console.c

···
 	spinlock_t c_ivq_lock;
 	spinlock_t c_ovq_lock;
 
-	/* The current config space is stored here */
-	struct virtio_console_config config;
+	/* max. number of ports this device can hold */
+	u32 max_nr_ports;
 
 	/* The virtio device we're associated with */
 	struct virtio_device *vdev;
···
 			break;
 		}
 		if (virtio32_to_cpu(vdev, cpkt->id) >=
-		    portdev->config.max_nr_ports) {
+		    portdev->max_nr_ports) {
 			dev_warn(&portdev->vdev->dev,
 				"Request for adding port with "
 				"out-of-bound id %u, max. supported id: %u\n",
-				cpkt->id, portdev->config.max_nr_ports - 1);
+				cpkt->id, portdev->max_nr_ports - 1);
 			break;
 		}
 		add_port(portdev, virtio32_to_cpu(vdev, cpkt->id));
···
 	u32 i, j, nr_ports, nr_queues;
 	int err;
 
-	nr_ports = portdev->config.max_nr_ports;
+	nr_ports = portdev->max_nr_ports;
 	nr_queues = use_multiport(portdev) ? (nr_ports + 1) * 2 : 2;
 
 	vqs = kmalloc(nr_queues * sizeof(struct virtqueue *), GFP_KERNEL);
···
 	}
 
 	multiport = false;
-	portdev->config.max_nr_ports = 1;
+	portdev->max_nr_ports = 1;
 
 	/* Don't test MULTIPORT at all if we're rproc: not a valid feature! */
 	if (!is_rproc_serial(vdev) &&
 	    virtio_cread_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
 				 struct virtio_console_config, max_nr_ports,
-				 &portdev->config.max_nr_ports) == 0) {
+				 &portdev->max_nr_ports) == 0) {
 		multiport = true;
 	}