can: dev: call netif_carrier_off() in register_candev()

CONFIG_CAN_LEDS is deprecated. When trying to use the generic netdev
trigger as suggested, there's a small inconsistency with the link
property: The LED is on initially, stays on when the device is brought
up, and then turns off (as expected) when the device is brought down.

Make sure the LED always reflects the state of the CAN device.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>