can: m_can: pci: Remove driver_data

driver_data is set to M_CAN_CLOCK_FREQ_EHL for all models. This change
was already five years ago, I don't expect any follow up models that
need to set a different frequency through the driver_data at this point.

Hardcode the M_CAN_CLOCK_FREQ_EHL. Once there are new models we can
evaluate what data needs to be in driver_data.

Acked-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com>
Signed-off-by: Markus Schneider-Pargmann (The Capable Hub) <msp@baylibre.com>
Reviewed-by: Vincent Mailhol <mailhol@kernel.org>
Link: https://patch.msgid.link/20260515-topic-mcan-pci-driverdata-v7-1-v2-1-e33e014ff328@baylibre.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>