can: isotp: add support for transmission without flow control

Usually the ISO 15765-2 protocol is a point-to-point protocol to transfer
segmented PDUs to a dedicated receiver. This receiver sends a flow control
message to specify protocol options and timings (e.g. block size / STmin).

The so called functional addressing communication allows a 1:N
communication but is limited to a single frame length.

This new CAN_ISOTP_CF_BROADCAST allows an unconfirmed 1:N communication
with PDU length that would not fit into a single frame. This feature is
not covered by the ISO 15765-2 standard.

Link: https://lore.kernel.org/all/20220507115558.19065-1-socketcan@hartkopp.net


Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>