catc: Use heap buffer for memory size test

Allocating USB buffers on the stack is not portable, and no longer
works on x86_64 (with VMAP_STACK enabled as per default).

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
static void catc_disconnect(struct usb_interface *intf)
{
	struct catc *catc = usb_get_intfdata(intf);

	usb_set_intfdata(intf, NULL);
	if (catc) {
		unregister_netdev(catc->netdev);
		usb_free_urb(catc->ctrl_urb);
		usb_free_urb(catc->tx_urb);
		usb_free_urb(catc->rx_urb);
		usb_free_urb(catc->irq_urb);
		free_netdev(catc->netdev);
	}
}

static void catc_disconnect(struct usb_interface *intf)
{
	struct catc *catc = usb_get_intfdata(intf);

	usb_set_intfdata(intf, NULL);
	if (catc) {
		unregister_netdev(catc->netdev);
		usb_free_urb(catc->ctrl_urb);
		usb_free_urb(catc->tx_urb);
		usb_free_urb(catc->rx_urb);
		usb_free_urb(catc->irq_urb);
		free_netdev(catc->netdev);
	}
}
