can: mcp251xfd: update macros describing ring, FIFO and RAM layout

So far the configuration of the hardware FIFOs is hard coded and
depend only on the selected CAN mode (CAN-2.0 or CAN-FD).

This patch updates the macros describing the ring, FIFO and RAM layout
to prepare for the next patches that add support for runtime
configurable ring parameters via ethtool.

Link: https://lore.kernel.org/20220313083640.501791-7-mkl@pengutronix.de


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