tools/testing/cxl: Fix some error exits

Fix a few typos where 'goto err_port' was used rather than the object
specific cleanup.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Link: https://lore.kernel.org/r/166752184255.947915.16163477849330181425.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>