ftmac100: use resource_size()

The calculation is off-by-one.  It should be "end - start + 1".  This
patch fixes it to use resource_size() instead.  Oddly, the code already
uses resource size correctly a couple lines earlier when it calls
request_mem_region() for this memory.
Signed-off-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ftmac100.c

@@ -1102,7 +1102,7 @@ static int ftmac100_probe(struct platform_device *pdev)
 		goto err_req_mem;
 	}
 
-	priv->base = ioremap(res->start, res->end - res->start);
+	priv->base = ioremap(res->start, resource_size(res));
 	if (!priv->base) {
 		dev_err(&pdev->dev, "Failed to ioremap ethernet registers\n");
 		err = -EIO;