can: fix oops caused by wrong rtnl newlink usage

For 'real' hardware CAN devices the netlink interface is used to set CAN
specific communication parameters. Real CAN hardware can not be created with
the ip tool ...

The invocation of 'ip link add type can' lead to an oops as the standard rtnl
newlink function was called:

http://bugzilla.kernel.org/show_bug.cgi?id=13954



This patch adds a private newlink function for the CAN device driver interface
that unconditionally returns -EOPNOTSUPP.

Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net>
Reported-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
CC: Patrick McHardy <kaber@trash.net>
CC: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>