r128: don't open-code memdup_user()

	xbuf_size = count * sizeof(*x);

	ybuf_size = count * sizeof(*y);

	x = kmalloc(xbuf_size, GFP_KERNEL);

	if (x == NULL)

		return -ENOMEM;

	y = kmalloc(ybuf_size, GFP_KERNEL);

	if (y == NULL) {

		kfree(x);

		return -ENOMEM;

	}

	if (copy_from_user(x, depth->x, xbuf_size)) {

		kfree(x);

		kfree(y);

		return -EFAULT;

	}

	if (copy_from_user(y, depth->y, xbuf_size)) {

	x = memdup_user(depth->x, xbuf_size);

	if (IS_ERR(x))

		return PTR_ERR(x);

	y = memdup_user(depth->y, ybuf_size);

	if (IS_ERR(y)) {

		kfree(x);

		kfree(y);

		return -EFAULT;

		return PTR_ERR(y);

	}

	buffer_size = depth->n * sizeof(u32);

	buffer = memdup_user(depth->buffer, buffer_size);

	if (IS_ERR(buffer)) {