This patch uses the previously added mcp251xfd_skb_set_timestamp()
function to convert the timestamp done by the CAN controller into a
proper skb hw timestamp.

Link: https://lore.kernel.org/r/20210304161209.2754463-1-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>