soc,southbridge/intel: Control SMI related FADT entries

When no SMI is installed, FADT should not advertise a trigger
mechanism that does not respond.

Change-Id: Ifb4f99c11a72e75ec20b9faaf62aed5546de91fa
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41909
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Subrata Banik <subrata.banik@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/intel/common/block/acpi/acpi.c b/src/soc/intel/common/block/acpi/acpi.c
index 70a9cac9..c4a0698 100644
--- a/src/soc/intel/common/block/acpi/acpi.c
+++ b/src/soc/intel/common/block/acpi/acpi.c
@@ -100,11 +100,12 @@
 	fadt->header.revision = get_acpi_table_revision(FADT);
 
 	fadt->sci_int = acpi_sci_irq();
-	fadt->smi_cmd = APM_CNT;
-	fadt->acpi_enable = APM_CNT_ACPI_ENABLE;
-	fadt->acpi_disable = APM_CNT_ACPI_DISABLE;
-	fadt->s4bios_req = 0x0;
-	fadt->pstate_cnt = 0;
+
+	if (CONFIG(HAVE_SMI_HANDLER)) {
+		fadt->smi_cmd = APM_CNT;
+		fadt->acpi_enable = APM_CNT_ACPI_ENABLE;
+		fadt->acpi_disable = APM_CNT_ACPI_DISABLE;
+	}
 
 	fadt->pm1a_evt_blk = pmbase + PM1_STS;
 	fadt->pm1b_evt_blk = 0x0;