can: raw: fix CAN FD frame transmissions over CAN XL devices

A CAN XL device is always capable to process CAN FD frames. The former
check when sending CAN FD frames relied on the existence of a CAN FD
device and did not check for a CAN XL device that would be correct
too.

With this patch the CAN FD feature is enabled automatically when CAN
XL is switched on - and CAN FD cannot be switch off while CAN XL is
enabled.

This precondition also leads to a clean up and reduction of checks in
the hot path in raw_rcv() and raw_sendmsg(). Some conditions are
reordered to handle simple checks first.

changes since v1: https://lore.kernel.org/all/20230131091012.50553-1-socketcan@hartkopp.net
- fixed typo: devive -> device
changes since v2: https://lore.kernel.org/all/20230131091824.51026-1-socketcan@hartkopp.net/


- reorder checks in if statements to handle simple checks first

Fixes: 62633269 ("can: raw: add CAN XL support")
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20230131105613.55228-1-socketcan@hartkopp.net


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>