soc/intel/xeon_sp/acpi: Fix uncore dsdt for multiple cpus

Fix the asl to use CONFIG_MAX_CPUS  to create entries for
multiple cpu uncores. Don't add the RTxx resource entries multiple
times. The function is called for each CPUs.

Change-Id: Ia4eb9716ae4bd72fb4eb98649105be629623cbef
Signed-off-by: Marc Jones <marcjones@sysproconsulting.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47060
Reviewed-by: Jay Talbott <JayTalbott@sysproconsulting.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/intel/xeon_sp/skx/soc_acpi.c b/src/soc/intel/xeon_sp/skx/soc_acpi.c
index df2550c..b392619 100644
--- a/src/soc/intel/xeon_sp/skx/soc_acpi.c
+++ b/src/soc/intel/xeon_sp/skx/soc_acpi.c
@@ -104,6 +104,10 @@
 	const IIO_UDS *hob = fsp_find_extension_hob_by_guid(uds_guid, &hob_size);
 	assert(hob != NULL && hob_size != 0);
 
+	/* Only add RTxx entries once. */
+	if (device->bus->secondary != 0)
+		return;
+
 	acpigen_write_scope("\\_SB");
 	for (int socket = 0; socket < hob->PlatformData.numofIIO; ++socket) {
 		IIO_RESOURCE_INSTANCE iio_resource =