Add driver for the Rockchip CAN-FD controller.

The IP core on the rk3568v2 SoC has 12 documented errata. Corrections
for these errata will be added in the upcoming patches.

Since several workarounds are required for the TX path, only add the
base driver that only implements the RX path.

Although the RX path implements CAN-FD support, it's not activated in
ctrlmode_supported, as the IP core in the rk3568v2 has problems with
receiving or sending certain CAN-FD frames.
Tested-by: Alibek Omarov <a1ba.omarov@gmail.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patch.msgid.link/20240904-rockchip-canfd-v5-4-8ae22bcb27cc@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>