Fix a potential NULL pointer dereference in mace_interrupt() in drivers/net/pcmcia/nmclan_cs.c

This patch fixes a potential null dereference bug where we dereference
DEV before a null check. This patch simply moves the dereferencing after
the null check.
Signed-off-by: NMicah Gruber <micah.gruber@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

drivers/net/pcmcia/nmclan_cs.c

@@ -996,7 +996,7 @@ static irqreturn_t mace_interrupt(int irq, void *dev_id)
 {
   struct net_device *dev = (struct net_device *) dev_id;
   mace_private *lp = netdev_priv(dev);
-  kio_addr_t ioaddr = dev->base_addr;
+  kio_addr_t ioaddr;
   int status;
   int IntrCnt = MACE_MAX_IR_ITERATIONS;
 
@@ -1006,6 +1006,8 @@ static irqreturn_t mace_interrupt(int irq, void *dev_id)
     return IRQ_NONE;
   }
 
+  ioaddr = dev->base_addr;
+
   if (lp->tx_irq_disabled) {
     printk(
       (lp->tx_irq_disabled?