With this patch the usage of the on-chip RAM is checked. In the
current driver the FIFO setup is fixed and always fits into the RAM.

With an upcoming patch series the ring and FIFO setup will be more
dynamic. Although using more RAM than available should not happen, but
add this safety check, just in case.

Link: https://lore.kernel.org/all/20220217103826.2299157-6-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>