The CAN_BUS_UNKNOWN CAN controller state is only used to indicate that
the current CAN controller state could not be read.
Remove it and change the signature of the can_get_state() API function
to return an integer indicating success or failure.
Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
Add optional user data argument to can_set_state_change_callback() to
comply with Zephyr API design guidelines.
Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
