drivers/net: eliminate irq handler impossible checks, needless casts

- Eliminate check for irq handler 'dev_id==NULL' where the
  condition never occurs.

- Eliminate needless casts to/from void*

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/eepro.c b/drivers/net/eepro.c
index aae454a..fd6e978 100644
--- a/drivers/net/eepro.c
+++ b/drivers/net/eepro.c
@@ -1198,17 +1198,11 @@
 static irqreturn_t
 eepro_interrupt(int irq, void *dev_id)
 {
-	struct net_device *dev =  (struct net_device *)dev_id;
-	                      /* (struct net_device *)(irq2dev_map[irq]);*/
+	struct net_device *dev = dev_id;
 	struct eepro_local *lp;
 	int ioaddr, status, boguscount = 20;
 	int handled = 0;
 
-	if (dev == NULL) {
-                printk (KERN_ERR "eepro_interrupt(): irq %d for unknown device.\\n", irq);
-                return IRQ_NONE;
-        }
-
 	lp = netdev_priv(dev);
 
         spin_lock(&lp->lock);