cxl/region: Fix cxlr_pmem leaks

cxl/region: Fix cxlr_pmem leaks

Before this error path, cxlr_pmem pointed to a kzalloc() memory, free
it to avoid this memory leaking.

Fixes: f17b558d6663 ("cxl/pmem: Refactor nvdimm device registration, delete the workqueue")
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20240428030748.318985-1-lizhijian@fujitsu.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>