cxl/decoder: Hide physical address information from non-root

Just like /proc/iomem, CXL physical address information is reserved for
root only.
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164298416650.3018233.450720006145238709.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/core/port.c

@@ -49,7 +49,7 @@ static ssize_t start_show(struct device *dev, struct device_attribute *attr,
 
 	return sysfs_emit(buf, "%#llx\n", cxld->range.start);
 }
-static DEVICE_ATTR_RO(start);
+static DEVICE_ATTR_ADMIN_RO(start);
 
 static ssize_t size_show(struct device *dev, struct device_attribute *attr,
 			char *buf)