cxacru: ignore cx82310_eth devices

Ignore ADSL routers, which can have the same vendor and product IDs
as ADSL modems but should be handled by the cx82310_eth driver.

This intentionally ignores device IDs that aren't currently handled
by cx82310_eth. There may be other device IDs that perhaps shouldn't
be claimed by cxacru.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>