platform/x86/intel/vsec: Add device links to enforce dependencies

New Intel VSEC features will have dependencies on other features, requiring
certain supplier drivers to be probed before their consumers. To enforce
this dependency ordering, introduce device links using device_link_add(),
ensuring that suppliers are fully registered before consumers are probed.

- Add device link tracking by storing supplier devices and tracking their
  state.
- Implement intel_vsec_link_devices() to establish links between suppliers
  and consumers based on feature dependencies.
- Add get_consumer_dependencies() to retrieve supplier-consumer
  relationships.
- Modify feature registration logic:
  * Consumers now check that all required suppliers are registered before
    being initialized.
  * suppliers_ready() verifies that all required supplier devices are
    available.
- Prevent potential null consumer name issue in sysfs:
  - Use dev_set_name() when creating auxiliary devices to ensure a
    unique, non-null consumer name.
- Update intel_vsec_pci_probe() to loop up to the number of possible
  features or when all devices are registered, whichever comes first.
- Introduce VSEC_CAP_UNUSED to prevent sub-features (registered via
  exported APIs) from being mistakenly linked.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Link: https://lore.kernel.org/r/20250703022832.1302928-5-david.e.box@linux.intel.com


Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>