dt-bindings: can: fsl,flexcan: add optional power-domains property

Add optional power-domains property for i.MX8 usage.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/all/20230328054602.1974255-1-peng.fan@oss.nxp.com


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