gpio/vr41xx: Convert use of struct resource to resource_size(ptr)

Remove miscellaneous use of direct calculation by using resource_size().
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/gpio/gpio-vr41xx.c

@@ -518,7 +518,7 @@ static int __devinit giu_probe(struct platform_device *pdev)
 	if (!res)
 		return -EBUSY;
 
-	giu_base = ioremap(res->start, res->end - res->start + 1);
+	giu_base = ioremap(res->start, resource_size(res));
 	if (!giu_base)
 		return -ENOMEM;