can: flexcan: add mcf5441x support

Add flexcan support for NXP ColdFire mcf5441x family.

This flexcan module is quite similar to imx6 flexcan module, but
with some exceptions:

- 3 separate interrupt sources, MB, BOFF and ERR,
- implements 16 mb only,
- m68k architecture is not supporting devicetrees, so a
  platform data check/case has been added,
- ColdFire is m68k, so big-endian cpu, with a little-endian flexcan
  module.

Link: https://lore.kernel.org/r/20210702094841.327679-5-angelo@kernel-space.org


Signed-off-by: Angelo Dureghello <angelo@kernel-space.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>