can: introduce the data bitrate configuration for CAN FD

As CAN FD offers a second bitrate for the data section of the CAN frame the
infrastructure for storing and configuring this second bitrate is introduced.
Improved the readability of the if-statement by inserting some newlines.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --cc drivers/net/can/dev.c
Simple merge

diff --cc include/linux/can/dev.h
Simple merge

diff --cc include/uapi/linux/can/netlink.h
Simple merge