Since commit

| 1f923440 ("dt-bindings: can: add can-controller.yaml")

there is a common CAN controller binding. Add this to the m_can
binding.

Link: https://lore.kernel.org/all/20220124220653.3477172-4-mkl@pengutronix.deReviewed-by: Chandrasekar Ramakrishnan <rcsekar@samsung.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>