ACPI / x86: boot: Don't setup SCI on HW-reduced platforms

As per note in 5.2.9 Fixed ACPI Description Table (FADT) chapter of ACPI
specification, on HW-reduced platforma OSPM should ignore fields related
to the ACPI HW register interface, one of which is SCI_INT.

Follow the spec and ignore any configuration done for interrupt line
defined by SCI_INT if FADT specifies a HW-reduced platform.

HW-reduced platforms will still be able to use SCI in case it provides
an override record in MADT table.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>