soc/intel/common: Improve Type16 SMBIOS tables

Use CAPID0_A to provide information closer to reality.

* Correctly advertise ECC support, max DIMM count and max capacity
* CAPID0_A hasn't changed since SNB, but most EDS mark the bits as
  reserved even though they are still used by FSP.
* Assume the same bits for Tiger Lake as for Ice Lake
* Assume the same bits for Skylake as for Coffee Lake
* Add CAPID0_A to Icelake headers

The lastest complete documentation can be found in Document: 341078-002.

Change-Id: I0d8fbb512fccbd99a6cfdacadc496d8266ae4cc7
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41334
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Christian Walter <christian.walter@9elements.com>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>

src/soc/intel/skylake/systemagent.c

@@ -87,3 +87,17 @@ int soc_get_uncore_prmmr_base_and_mask(uint64_t *prmrr_base,
 	*prmrr_mask = (uint64_t) msr.hi << 32 | msr.lo;
 	return 0;
 }
+
+uint32_t soc_systemagent_max_chan_capacity_mib(u8 capid0_a_ddrsz)
+{
+	switch (capid0_a_ddrsz) {
+	case 1:
+		return 8192;
+	case 2:
+		return 4096;
+	case 3:
+		return 2048;
+	default:
+		return 32768;
+	}
+}