virtio: rng: remove unused struct element

vdev is unused in struct virtrng_info, remove it.

CC: Amos Kong <akong@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/char/hw_random/virtio-rng.c

@@ -28,7 +28,6 @@
 static DEFINE_IDA(rng_index_ida);
 
 struct virtrng_info {
-	struct virtio_device *vdev;
 	struct hwrng hwrng;
 	struct virtqueue *vq;
 	unsigned int data_avail;