can: j1939: transport: j1939_session_skb_drop_old(): spin_unlock_irqrestore() before kfree_skb()

It is not allowed to call kfree_skb() from hardware interrupt context
or with interrupts being disabled. The skb is unlinked from the queue,
so it can be freed after spin_unlock_irqrestore().

Fixes: 9d71dd0c ("can: add support of SAE J1939 protocol")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/all/20221027091237.2290111-1-yangyingliang@huawei.com


Cc: stable@vger.kernel.org
[mkl: adjust subject]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>