omap: Use resource_size

Use the resource_size function instead of manually calculating the
resource size. This reduces the chance of introducing off-by-one errors
and actually fixes one in mailbox.c.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/gpmc.c

@@ -366,7 +366,7 @@ int gpmc_cs_request(int cs, unsigned long size, unsigned long *base)
 	if (r < 0)
 		goto out;
 
-	gpmc_cs_enable_mem(cs, res->start, res->end - res->start + 1);
+	gpmc_cs_enable_mem(cs, res->start, resource_size(res));
 	*base = res->start;
 	gpmc_cs_set_reserved(cs, 1);
 out:

arch/arm/mach-omap2/mailbox.c

@@ -300,7 +300,7 @@ static int __devinit omap2_mbox_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "invalid mem resource\n");
 		return -ENODEV;
 	}
-	mbox_base = ioremap(res->start, res->end - res->start);
+	mbox_base = ioremap(res->start, resource_size(res));
 	if (!mbox_base)
 		return -ENOMEM;