can: m_can: convert indention to kernel coding style

This patch converts the  indention in the m_can driver to kernel coding style.

Link: https://lore.kernel.org/r/20201212175518.139651-3-mkl@pengutronix.de


Reviewed-by: Sean Nyekjaer <sean@geanix.com>
Reviewed-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>