platform/x86/intel/vsec: Refactor base_addr handling

platform/x86/intel/vsec: Refactor base_addr handling

The base_addr field in intel_vsec_platform_info was originally added to
support devices that emulate PCI VSEC capabilities in MMIO. Previously,
the code would check at registration time whether base_addr was set,
falling back to the PCI BAR if not.

Refactor this by making base_addr an explicit function parameter. This
clarifies ownership of the value and removes conditional logic from
intel_vsec_add_dev(). It also enables making intel_vsec_platform_info
const in a later patch, since the function no longer needs to write to
info->base_addr.

No functional change intended.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Link: https://patch.msgid.link/20260313015202.3660072-2-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>