can: ctucanfd: add support for CTU CAN FD open-source IP core - bus independent part.

This driver adds support for the CTU CAN FD open-source IP core.
More documentation and core sources at project page
(https://gitlab.fel.cvut.cz/canbus/ctucanfd_ip_core).
The core integration to Xilinx Zynq system as platform driver
is available (https://gitlab.fel.cvut.cz/canbus/zynq/zynq-can-sja1000-top).
Implementation on Intel FPGA based PCI Express board is available
from project (https://gitlab.fel.cvut.cz/canbus/pcie-ctucanfd).

More about CAN bus related projects used and developed at CTU FEE at
https://canbus.pages.fel.cvut.cz/ .

Link: https://lore.kernel.org/all/1906e4941560ae2ce4b8d181131fd4963aa31611.1647904780.git.pisa@cmp.felk.cvut.cz
Signed-off-by: Martin Jerabek <martin.jerabek01@gmail.com>
Signed-off-by: Ondrej Ille <ondrej.ille@gmail.com>
Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>