can: netlink: add initial CAN XL support

can: netlink: add initial CAN XL support

CAN XL uses bittiming parameters different from Classical CAN and CAN
FD. Thus, all the data bittiming parameters, including TDC, need to be
duplicated for CAN XL.

Add the CAN XL netlink interface for all the features which are common
with CAN FD. Any new CAN XL specific features are added later on.

The first time CAN XL is activated, the MTU is set by default to
CANXL_MAX_MTU. The user may then configure a custom MTU within the
CANXL_MIN_MTU to CANXL_MAX_MTU range, in which case, the custom MTU
value will be kept as long as CAN XL remains active.

Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20251126-canxl-v8-5-e7e3eb74f889@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>