can: m_can: add infrastructure for internal timestamps

Add infrastucture to allow internal timestamps from the M_CAN to be
configured and retrieved.

Link: https://lore.kernel.org/r/20210308102427.63916-2-torin@maxiluxsystems.com
Signed-off-by: Torin Cooper-Bennun <torin@maxiluxsystems.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>