Add missing attribute validation for IFLA_CAN_TERMINATION
to the netlink policy.

Fixes: 12a6075c ("can: dev: add CAN interface termination API")
Signed-off-by: NJakub Kicinski <kuba@kernel.org>
Acked-by: NOliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>