can: raw: add support for SO_MARK

Add support for SO_MARK to the CAN_RAW protocol. This makes it
possible to add traffic control filters based on the fwmark.

Link: https://lore.kernel.org/all/20221210113653.170346-1-mkl@pengutronix.deAcked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

net/can/raw.c

@@ -857,6 +857,7 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 
 	skb->dev = dev;
 	skb->priority = sk->sk_priority;
+	skb->mark = sk->sk_mark;
 	skb->tstamp = sockc.transmit_time;
 
 	skb_setup_tx_timestamp(skb, sockc.tsflags);