drivers: can: propagate CAN controller operation mode to CAN transceiver

Propagate the current CAN controller operation mode to the CAN transceiver
when enabling it.

Some more advanced CAN transceivers, especially those supporting Partial
Networking (CAN PN), require knowledge of the intended CAN operation mode
(e.g. normal mode vs. listen-only mode).

This commit simply prepares the CAN transceiver API for supporting such CAN
transceivers, although no in-tree drivers require this information yet.

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>