platform/x86/intel/vsec: Move structures to header

In preparation for exporting an API to register Intel Vendor Specific
Extended Capabilities (VSEC) from other drivers, move needed structures to
the header file.

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/20231129222132.2331261-4-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>