can: etas_es58x: es58x_rx_err_msg(): fix memory leak in error path

In es58x_rx_err_msg(), if can->do_set_mode() fails, the function
directly returns without calling netif_rx(skb). This means that the
skb previously allocated by alloc_can_err_skb() is not freed. In other
terms, this is a memory leak.

This patch simply removes the return statement in the error branch and
let the function continue.

Issue was found with GCC -fanalyzer, please follow the link below for
details.

Fixes: 85372578 ("can: etas_es58x: add core support for ETAS ES58X CAN USB interfaces")
Link: https://lore.kernel.org/all/20211026180740.1953265-1-mailhol.vincent@wanadoo.frSigned-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/etas_es58x/es58x_core.c

@@ -664,7 +664,7 @@ int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error,
 	struct can_device_stats *can_stats = &can->can_stats;
 	struct can_frame *cf = NULL;
 	struct sk_buff *skb;
-	int ret;
+	int ret = 0;
 
 	if (!netif_running(netdev)) {
 		if (net_ratelimit())
@@ -823,8 +823,6 @@ int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error,
 			can->state = CAN_STATE_BUS_OFF;
 			can_bus_off(netdev);
 			ret = can->do_set_mode(netdev, CAN_MODE_STOP);
-			if (ret)
-				return ret;
 		}
 		break;
 
@@ -881,7 +879,7 @@ int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error,
 					ES58X_EVENT_BUSOFF, timestamp);
 	}
 
-	return 0;
+	return ret;
 }
 
 /**