can: m_can: m_can_init_ram(): make static
Since commit eaacfeaca7ad ("can: m_can: Call the RAM init directly from
m_can_chip_config") m_can_init_ram() is not used outside of m_can.c.
Mark as static and remove the EXPORT_SYMBOL_GPL().
Link: https://patch.msgid.link/20251008-m_can-cleanups-v1-1-1784a18eaa84@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>