platform/x86/intel/vsec: Assign auxdev parent by argument

Instead of checking for a NULL parent argument in intel_vsec_add_aux() and
then assigning it to the probed device, remove this check and just pass the
device in the call. Since this function is exported, return -EINVAL if the
parent is not specified.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231129222132.2331261-7-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>