ntb_netdev: Fix list_for_each_entry exit issue

If list_for_each_entry exits without finding the ntb_device, the dev
pointer will not be NULL.  Thus the check will never be true and the
code will not exit when it should.  Correct this by adding a bool to
determine when the device is found, otherwise exit in good fashion.
Signed-off-by: Jon Mason <jon.mason@intel.com>

drivers/net/ntb_netdev.c

@@ -367,12 +367,15 @@ static void ntb_netdev_remove(struct pci_dev *pdev)
 {
 	struct net_device *ndev;
 	struct ntb_netdev *dev;
+	bool found  = false;
 
 	list_for_each_entry(dev, &dev_list, list) {
-		if (dev->pdev == pdev)
+		if (dev->pdev == pdev) {
+			found = true;
 			break;
+		}
 	}
-	if (dev == NULL)
+	if (!found)
 		return;
 
 	list_del(&dev->list);