cdc_ether: add Novatel USB551L device IDs for FLAG_WWAN

Needs to be tagged with FLAG_WWAN, which since it has generic
descriptors, won't happen if we don't override the generic
driver info.

Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable@vger.kernel.org
Signed-off-by: Dan Williams <dcbw@redhat.com>
Acked-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: David S. Miller <davem@davemloft.net>