drivers/net: Eliminate a NULL pointer dereference

At the point of the print, dev is NULL.

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

// <smpl>
@r exists@
expression E,E1;
identifier f;
statement S1,S2,S3;
@@

if ((E == NULL && ...) || ...)
{
  ... when != if (...) S1 else S2
      when != E = E1
* E->f
  ... when any
  return ...;
}
else S3
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/3c507.c

@@ -551,8 +551,7 @@ static irqreturn_t el16_interrupt(int irq, void *dev_id)
 	void __iomem *shmem;
 
 	if (dev == NULL) {
-		pr_err("%s: net_interrupt(): irq %d for unknown device.\n",
-			dev->name, irq);
+		pr_err("net_interrupt(): irq %d for unknown device.\n", irq);
 		return IRQ_NONE;
 	}