cxl: Simplify cxl_root_ops allocation and handling

cxl: Simplify cxl_root_ops allocation and handling

A root port's callback handlers are collected in struct cxl_root_ops.
The structure is dynamically allocated, though it contains only a
single pointer in it. This also requires to check two pointers to
check for the existance of a callback.

Simplify the allocation, release and handler check by embedding the
ops statically in struct cxl_root.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Link: https://patch.msgid.link/20260114164837.1076338-5-rrichter@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>