soc/intel/xeon_sp: Enable SMI handler

SMI handler was not installed for Xeon_sp platforms. This enables SMM
relocation and SMI handling.

TESTED:
- SMRR are correctly set
- The save state revision is correct (0x00030101)
- SMI's are properly generated and handled
- SMM MSR save state are not supported, so relocate SMM on all cores
in series
- Verified on OCP/Deltalake mainboard.

NOTE:
- Code for accessing a CPU save state is not working for SMMLOADERV2,
so some SMM features like GSMI, SMMSTORE, updating the ACPI GNVS
pointer are not supported.
- This hooks up to some soc/intel/common like TCO and ACPI GNVS. GNVS
is broken and needs to be fixed separately. It is unknown if TCO is
supported. This might require a cleanup in the future.

Change-Id: Iabee5c72f0245ab988d477ac8df3d8d655a2a506
Signed-off-by: Rocky Phagura <rphagura@fb.com>
Signed-off-by: Christian Walter <christian.walter@9elements.com>
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46231
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/Kconfig b/src/soc/intel/xeon_sp/cpx/Kconfig
index 28e7b83..369d474 100644
--- a/src/soc/intel/xeon_sp/cpx/Kconfig
+++ b/src/soc/intel/xeon_sp/cpx/Kconfig
@@ -78,6 +78,10 @@
 	  documentation says this needs to be at least 128KiB, but practice
 	  show this needs to be 256KiB or more.
 
+config IED_REGION_SIZE
+	hex
+	default 0x400000
+
 config SOC_INTEL_COMMON_BLOCK_P2SB
 	def_bool y