can: softing: softing_main: ensure a consistent return value in error case

Typically, the return value desired for the failure of a function with an
integer return value is a negative integer. In these cases, the return
value is sometimes a negative integer and sometimes 0, due to a subsequent
initialization of the return variable within the loop.

A simplified version of the semantic match that finds this problem is:
(http://coccinelle.lip6.fr/)

//<smpl>
@r exists@
identifier ret;
position p;
constant C;
expression e1,e3,e4;
statement S;
@@

ret = -C
... when != ret = e3
when any
if@p (...) S
... when any
if (\(ret != 0\|ret < 0\|ret > 0\) || ...) { ... return ...; }
... when != ret = e3
when any
*if@p (...)
{
... when != ret = e4
return ret;
}
//</smpl>

Signed-off-by: Julia Lawall <[e-mail]>
Acked-by: Kurt Van Dijck <[e-mail]>
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/softing/softing_main.c

···
 		goto sysfs_failed;
 	}
 
-	ret = -ENOMEM;
 	for (j = 0; j < ARRAY_SIZE(card->net); ++j) {
 		card->net[j] = netdev =
 			softing_netdev_create(card, card->id.chip[j]);
 		if (!netdev) {
 			dev_alert(&pdev->dev, "failed to make can[%i]", j);
+			ret = -ENOMEM;
 			goto netdev_failed;
 		}
 		priv = netdev_priv(card->net[j]);