drivers/block/mg_disk.c: use resource_size()

Use resource_size() for ioremap.

The ioremap appears to be passing the incorrect size for the platform
resource.  Unfortunately, I can't locate a user in mainline to verify
this.  Using resource_size should be the correct fix.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: unsik Kim <donari75@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

drivers/block/mg_disk.c

@@ -860,7 +860,7 @@ static int mg_probe(struct platform_device *plat_dev)
 		err = -EINVAL;
 		goto probe_err_2;
 	}
-	host->dev_base = ioremap(rsc->start , rsc->end + 1);
+	host->dev_base = ioremap(rsc->start, resource_size(rsc));
 	if (!host->dev_base) {
 		printk(KERN_ERR "%s:%d ioremap fail\n",
 				__func__, __LINE__);