can: purge socket error queue on sock destruct

CAN supports software tx timestamps as of the below commit. Purge
any queued timestamp packets on socket destroy.

Fixes: 51f31cab

 ("ip: support for TX timestamps on UDP and RAW sockets")
Reported-by:  <syzbot+a90604060cb40f5bdd16@syzkaller.appspotmail.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>