virtio-rng: fix boot with virtio-rng device

Commit "virtio-rng: support multiple virtio-rng devices" has broken
boot with a virtio-rng device because the 'init' callback of the
virtio-rng device was left unitialized to garbage, and got called
by the hwrng infrastructure, killing the guest on boot.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fixes: 08e53fb

drivers/char/hw_random/virtio-rng.c

@@ -95,7 +95,7 @@ static int probe_common(struct virtio_device *vdev)
 	int err, i;
 	struct virtrng_info *vi = NULL;
 
-	vi = kmalloc(sizeof(struct virtrng_info), GFP_KERNEL);
+	vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL);
 	vi->hwrng.name = kmalloc(40, GFP_KERNEL);
 	init_completion(&vi->have_data);