soc/intel/mtl: Do initial Meteor Lake SoC commit till ramstage

List of changes:
1. Add required SoC programming till ramstage
2. Include only required headers into include/soc
3. Fill required FSP-S UPD to call FSP-S API

BUG=b:224325352
TEST= Build 'util/abuild/abuild -p none -t google/rex -a -c max'.

Signed-off-by: Ravi Sarawadi <ravishankar.sarawadi@intel.com>
Change-Id: Ie746c0bfcf1f315a4ab6f540cc7c4933157551d7
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63364
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Tarun Tuli <taruntuli@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/meteorlake/gspi.c

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <intelblocks/gspi.h>
+#include <soc/pci_devs.h>
+
+int gspi_soc_bus_to_devfn(unsigned int gspi_bus)
+{
+	switch (gspi_bus) {
+	case 0:
+		return PCI_DEVFN_GSPI0;
+	case 1:
+		return PCI_DEVFN_GSPI1;
+	}
+	return -1;
+}