can: softing: softing_netdev_open(): fix error handling

If softing_netdev_open() fails, we should call close_candev() to avoid
reference leak.

Fixes: 03fd3cf5 ("can: add driver for Softing card")
Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
Acked-by: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
Link: https://lore.kernel.org/r/20201202151632.1343786-1-zhangqilong3@huawei.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20201204133508.742120-2-mkl@pengutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/can/softing/softing_main.c

@@ -382,8 +382,13 @@ static int softing_netdev_open(struct net_device *ndev)
 
 	/* check or determine and set bittime */
 	ret = open_candev(ndev);
-	if (!ret)
-		ret = softing_startstop(ndev, 1);
+	if (ret)
+		return ret;
+
+	ret = softing_startstop(ndev, 1);
+	if (ret < 0)
+		close_candev(ndev);
+
 	return ret;
 }