soc/intel/xeon_sp/cpx: Add soc_acpi_fill_fadt()

Prepare for common ACPI code. Make acpi_fill_fadt() match
intel/commom/block/acpi/acpi.c function. Use soc_acpi_fill_fadt()
to set cpx fadt->flags.

Change-Id: I9c04dd478aa5e0f1467e63d06da094128edd9650
Signed-off-by: Marc Jones <marcjones@sysproconsulting.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45845
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Jay Talbott <JayTalbott@sysproconsulting.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/intel/xeon_sp/cpx/soc_acpi.c b/src/soc/intel/xeon_sp/cpx/soc_acpi.c
index db1d3d2..d0b82e5 100644
--- a/src/soc/intel/xeon_sp/cpx/soc_acpi.c
+++ b/src/soc/intel/xeon_sp/cpx/soc_acpi.c
@@ -52,6 +52,13 @@
 	return pci_read_config32(dev, PMC_ACPI_CNT);
 }
 
+void soc_fill_fadt(acpi_fadt_t *fadt)
+{
+	/* Clear flags set by common/block/acpi/acpi.c acpi_fill_fadt() */
+	fadt->flags &=  ~(ACPI_FADT_SLEEP_BUTTON | ACPI_FADT_SEALED_CASE |
+				ACPI_FADT_S4_RTC_WAKE);
+}
+
 /*
  * Currently called in southbridge_inject_dsdt(). Change to soc_southbridge_inject_dsdt()
  * with a call from the common/function or find another way to call this at the correct place