can: m_can: fix typo prescalar -> prescaler

This patch fixes the typo prescalar -> prescaler.

Link: https://lore.kernel.org/all/20220610112037.3857192-1-mkl@pengutronix.de
Reviewed-by: Chandrasekar Ramakrishnan <rcsekar@samsung.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>