Merge branch 'document-polarfire-soc-can-controller'

Conor Dooley says:

====================
When adding the dts for PolarFire SoC, the can controllers were
omitted, so here they are...
====================

Link: https://lore.kernel.org/all/20220607065459.2035746-1-conor.dooley@microchip.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>