cxl/port: Replace put_cxl_root() by a cleanup helper

cxl/port: Replace put_cxl_root() by a cleanup helper

Function put_cxl_root() is only used by its cleanup helper. Remove the
function entirely and only use the helper.

Signed-off-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: "Fabio M. De Francesco" <fabio.m.de.francesco@linux.intel.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20250509150700.2817697-9-rrichter@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>